2015s-44
Social Norms and Legal Design
Bruno Deffains, Claude Fluet
Série Scientifique/Scientific Series
2015s-44
Social Norms and Legal Design
Bruno Deffains, Claude Fluet
Série Scientifique
Scientific Series
Montréal
Septembre/September 2015
© 2015 Bruno Deffains, Claude Fluet. Tous droits réservés. All rights reserved. Reproduction partielle permise
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Social Norms and Legal Design*
Bruno Deffains†, Claude Fluet‡
Résumé/abstract
We compare fault-based and strict liability offences in law enforcement when behavior is influenced by
informal prosocial norms of conduct. Fault tends to be more effective than strict liability in harnessing
social or self-image concerns. When enforcement relies on fines and assessing fault is not too costly, the
optimal legal regime is fault-based with a standard consistent with the underlying social norm if
convictions would seldom occur under optimal enforcement; otherwise liability should be strict. When
sanctions are nonmonetary or when stigmatization imposes a deadweight loss, the legal standard may
be harsher or more lenient than the social norm.
Mots clés/keywords : Social preferences, regulatory offences, law enforcement,
strict liability, fault, legal standard, compliance, deterrence
Codes JEL/JEL Codes : D8, K4, Z13
*
We thank the participants of the CESifo Law and Economics 2011 Workshop , the 4th Law and Economics
Theory Conference at Berkeley, the PET and ALEA conferences in 2015, and of seminars at the universities of
Aix-Marseille, Bonn, Haifa, Lausanne, Laval, Lorraine, Mannheim, Nanterre, Tel-Aviv, Toulouse, Vanderbilt
and Yale. Financial support from SSHRC Canada is gratefully acknowledged (SSHRC 435-2023-1671).
†
Université Panthéon Assas and Institut Universitaire de France. E-mail:
[email protected]
‡
Université Laval, CIRPEE and CRED. E-mail:
[email protected]
Social Norms and Legal Design
Bruno De¤ains
Claude Fluetyz
This version, September 2015
Abstract
We compare fault-based and strict liability o¤ences in law enforcement when behavior is in‡uenced by informal prosocial norms of conduct. Fault tends to be more e¤ective than strict liability in harnessing social or self-image concerns. When enforcement relies on …nes
and assessing fault is not too costly, the optimal legal regime is faultbased with a standard consistent with the underlying social norm if
convictions would seldom occur under optimal enforcement; otherwise
liability should be strict. When sanctions are nonmonetary or when
stigmatization imposes a deadweight loss, the legal standard may be
harsher or more lenient than the social norm.
KEYWORDS: Social preferences, regulatory o¤ences, law enforcement,
strict liability, fault, legal standard, compliance, deterrence. (JEL: D8,
K4, Z13)
Université Panthéon Assas and Institut Universitaire de France.
E-mail:
Bruno.De¤
[email protected]
y
Université Laval, CIRPEE and CRED. E-mail:
[email protected]
z
We thank the participants of the CESifo Law and Economics 2011 Workshop , the
4th Law and Economics Theory Conference at Berkeley, the PET and ALEA conferences
in 2015, and of seminars at the universities of Aix-Marseille, Bonn, Haifa, Lausanne,
Laval, Lorraine, Mannheim, Nanterre, Tel-Aviv, Toulouse, Vanderbilt and Yale. Financial
support from SSHRC Canada is gratefully acknowledged (SSHRC 435-2023-1671).
1
Introduction
Illegal behavior ranges from crimes of great antiquity such as murder carrying strong moral opprobrium down to lesser ‘quasi-crimes’, e.g., misleading
advertising, tax noncompliance or …shing out of season. An important issue
in legal design is the categorization of o¤ences. Should they be criminalized
or quali…ed as mere violations? Legal systems have been dealing with this
question since the mid 19th century owing to the multiplication of modern regulatory o¤ences, e.g., in factory legislation or food and drug laws.
There has been a resurgence of the issue in the wake of the recent criminal law reforms in many countries. It is also debated in new …elds of law
such as competition law, …nancial regulations and environmental protection
legislation.
In their survey of the economic theory of public law enforcement, Polinsky and Shavell (2007) discuss the various policy choices facing the state,
one of which concerns the sanctioning rule: “The rule could be strict in the
sense that a party is sanctioned whenever he has been found to have caused
harm (or expected harm). Alternatively, the rule could be fault-based, meaning that a party who has been found to have caused harm is sanctioned only
if he failed to obey some standard of behavior or regulatory requirement.”
Whether there should be strict liability crimes is nevertheless contentious.
To give but two examples, the Model Penal Code of the American Law Institute in the 1960s rejected the principle of strict liability in criminal law.
By contrast, in the 1990s Australia reformed its criminal code squarely on
the basis of the fault-based versus strict liability dichotomy.1
We analyze this legal design issue from the perspective of harnessing
1
For a glimpse of the debates in other countries, see Law Reform Commission of Canada
(1974), Faure and Heine (2005), Horder (2005), Simester (2005), Spencer and Pedain
(2005), Wils (2007), and Law Commission (2010). For earlier in‡uential discussions, see
Kadish (1963) and Fitzgerald (1965). For recent assessments of the evolution in the US,
see Singer (1989) and Brown (2012).
1
normative motivations. The standard model of legal enforcement is extended
to incorporate social preferences and pre-existing socially e¢cient norms of
conduct. At one extreme, the social norm has little salience (e.g., few people
feel concerned) so that policy prescriptions are the same as in the standard
model without social preferences. At the other extreme, the social norm
has high salience. Individuals who are thought not to care meet strong
disapproval, a source of disutility. We inquire how the salience of the social
norm, together with social or self-image concerns with respect to deviations
from the norm, a¤ects the relative performance of fault-based versus strict
liability o¤ences from a deterrence and enforcement cost point of view.
As in the standard model, society faces a trade-o¤ between enforcement
costs and the deterrence of socially undesirable behavior. The law may be
under-enforced because enforcement is costly. Nevertheless, some individuals behave e¢ciently from a social point of view. Some do so out of intrinsic
moral or prosocial predispositions. Others have no such predispositions but
would like people to believe that they do or perhaps would want to perceive
themselves as having such concerns; that is, they care about social approval
or self image. To the extent that informal motivations su¢ce, legal enforcement is of course super‡uous. We consider situations where an individual’s
actions are only vaguely observable by one’s reference group or would only
be self-servingly recalled by the individual himself. However, convictions
for o¤ences provide hard information from which inferences can be drawn
about the intrinsic predispositions of the individuals involved. Under either fault-based or strict liability o¤ences, social and self image concerns
therefore provide incentives to mimic the virtuous.
A basic result of our analysis is that fault-based o¤ences tend to be more
e¤ective in harnessing image concerns. Legal sanctions are then more informative. A strict liability o¤ence conveys that the o¤ender committed a
harmful action but says nothing about the circumstances in which the action
was committed. A fault-based o¤ence unambiguously reveals reprehensible
2
behavior, thereby providing more precise information about the individual’s
character. When the social norm has high salience with potentially strong
stigmatization of violators, socially useful incentives are therefore provided
by the signaling role of fault, allowing greater deterrence or lower enforcement costs. When the social norm has relatively low salience, however, it
may be that strict liability does better in harnessing image concerns. The
optimal legal regime and enforcement policy are interdependent and depend in a complex way on the underlying situation. When the norm has
high salience and assessing fault is not too costly, the best regime is faultbased. If enforcement relies on …nes, the optimal legal standard of fault
then replicates the underlying social norm and convictions are rare events
under the optimal enforcement policy. Otherwise, when the best regime is
strict liability, convictions (and therefore o¤ences) are frequent events. With
nonmonetary sanctions such as imprisonment or when stigmatization e¤ects
entail a social deadweight loss, other considerations come into play. Under
an optimal fault-based regime, the legal standard of fault may then be more
lenient than the underlying social norm.
The dichotomy between fault-based and strict liability o¤ences partly
captures the distinction between “criminalized” o¤ences and purely “regulatory” o¤ences. In our analysis, the legal design problem is approached
from a standard utilitarian perspective. The stigmatization e¤ects of legal
sanctions are considered for their incentive properties. Fault-based o¤ences
tend to do better for acts that are clearly bad from a moral or social point
of view. When there is only a weak pre-existing norm, strict liability does as
well and is less costly. Our analysis therefore provides an economic interpretation of the usefulness of the distinction between malum in se and malum
prohibitum 2 for optimal legal design and enforcement (see the discussion in
2
Malum in se means wrong or reprehensible in itself independently of regulations or
laws. Malum prohibitum refers to conduct that is wrong only because it is prohibited by
law. The di¤erence is often decribed in terms of iussum quia iustum and iustum quia
iussum, namely something that is commanded (iussum ) because it is just (iustum ) and
3
Dau-Schmidt, 1990).
Section 2 reviews some of the relevant literature. Section 3 presents the
basic setup. Section 4 compares the incentives under di¤erent legal regimes
and enforcement policies. Section 5 derives the implications for e¢cient
legal design when enforcement relies on …nes. Section 6 extends the analysis
to nonmonetary sanctions and discusses the possibility that stigmatization
entails a deadweight loss. Section 7 concludes. Proofs are in the Appendix.
2
Literature review
Our analysis belongs to a recent microeconomic literature on social preferences emphasizing that one’s actions may reveal unobservable predispositions and that some predispositions are socially valued, hence social pressure may in‡uence behavior through the individuals’ image concerns (e.g.,
Bernheim 1994, Bénabou and Tirole 2006, 2011, Daughety and Reinganum,
2010). Numerous experimental or …eld studies show that image concerns
are important motivators of prosocial behavior (Masclet et al. 2003, Dana
et al. 2006, Ellingsen and Johannesson 2008, Andreoni and Bernheim 2008,
Ariely et al. 2010, Funk 2010, Lacetera and Macis 2010, among others).
Another strand of literature deals with the interaction between formal
legal sanctions and informal nonlegal sanctions. Part of this literature analyzes the substitutability between legal and nonlegal sanctions, stressing
that stigma or loss of standing in a community may deter undesirable behavior just as or more e¤ectively than formal legal sanctions (Macauley
1963; Ellickson 1991; Bernstein 1992). Another part discusses the potential
complementarity between formal and informal sanctions, noting that legal
penalties may in‡uence the existence and impact of informal sanctions (Kahan, 1998, Posner 2000; Cooter 2000a, 2000b; Teichman 2005; Iacobucci
something that is just (iustum ) because it is commanded (iussum ).
4
2014). This also relates to the role of stigma and shaming penalties in relation to criminal activity; see Rasmusen (1996), Harel and Clement (2007),
and Zasu (2007) among others.
The “norms and law” literature also discusses the relationship between
morality and law. Posner (1997), Shavell (2002), and McAdams and Rasmusen (2007) provide a general discussion of legal sanctions versus informal
motivations as regulators of conduct. Shavell compares the two in terms of
the social costs of enforcement and the e¤ectiveness in controlling behavior.
He argues that, if the expected private gain from undesirable action and
the expected harm due to the conduct are large, it is optimal to have law
supplement morality and, if morality does not function well, law alone is
optimal. Mialon (2014) analyzes the e¤ectiveness of moral norms in an evolutionary context, showing that legal rules may be necessary when norms
are easily swayed by social interaction in the long run. Legal design also
bears a relation to the concept of “expressive law”. According to this view
even “mild law”, i.e., law backed by small nondeterrent sanctions or weakly
enforced, can have desirable e¤ects on behavior; see Cooter (1998b), Tyran
and Feld (2006), and Galbiati and Vertova (2008, 2014).
In a paper related to the present one, although in a civil litigation context, De¤ains and Fluet (2013) model how tort rules and social pressure
interact to provide incentives to take care. In their analysis, the extent to
which liability rules are privately enforced and the characteristics of the tort
rules themselves are taken as given, e.g., if found liable the injurer must pay
compensatory damages to the victim. In the present paper we consider legal
design together with optimal public law enforcement. The design problem
is whether o¤ences should be strict or fault-based and the determination
of the legal standard of fault in the latter case. Enforcement concerns the
detection of violations and the setting of sanctions, whether monetary or
nonmonetary.
5
3
Set-Up
We start with a simple version of the economic model of public law enforcement.3 The model analyzes the use of legal rules for preventing socially
harmful behavior and of public agents to detect and punish o¤enders. In the
standard model, individuals violate the law when their private net bene…t
from doing so is positive given the risk of legal sanctions. We use this framework to de…ne strict liability and fault-based o¤ences. Next we extend the
framework to incorporate social preferences.
The standard model. Risk-neutral individuals obtain a private gain
g from committing an act that causes an external harm of amount h. The
private gain, equivalently the opportunity cost of not committing the act,
varies between individuals and depends on the circumstances.4 The probability distribution is F (g) with density f (g) on the support [0; g], where
g > h. Social welfare is the sum of the gains individuals obtain from committing the act less the harm they cause to others. Denoting behavior by
e 2 f0; 1g, where e = 1 means commission of the act, and denoting with
e(g) the behavior in the circumstance g, social welfare is
Z
g
e(g) (g
h) f (g) dg:
0
Socially optimal behavior is
e (g) =
1 if g h;
0 otherwise.
(1)
The harmful act is assumed to be sometimes socially warranted, allowing a
meaningful distinction between strict liability and fault-based legal regimes.
3
Well known surveys are Polinsky and Shavell (2000, 2007). We di¤er by explicitly
introducing a costs of ascertaining fault.
4
Acts can be interpreted from di¤erent perspectives, namely acts of “omission” (not
complying with some regulation, e.g., …re detectors) versus “positive” acts (driving
through red lights).
6
The harmful act is quali…ed as a strict liability o¤ence if it is illegal
irrespective of circumstances. For the time being the sanction for violating
the law is taken to be a …ne s, a socially costless transfer of money. The
enforcement cost is c(p) where p is the probability of detecting harmful acts
and c(p) is the per capita expenditure with derivatives c0 > 0, c00
0.
An individual does not comply with the law if his private gain exceeds the
expected …ne, g
ps. For a given enforcement policy, welfare is therefore
Z g
(g h) f (g) dg c(p):
ps
An optimal policy maximizes this expression with respect to the value of
the …ne and the probability of detection. Becker’s (1968) maximum sanction
principle applies: to economize on detection costs, the …ne should be set at
the highest feasible level, say the individuals’ wealth or some given upper
bound on allowable …nes which we denote by sM . Given the maximal …ne,
welfare is maximized with respect to the probability of detection. Assuming
an interior solution, the …rst-order condition is
(h
psM )
dF (psM )
= c0 (p):
dp
(2)
The left-hand side is the marginal social bene…t from deterrence, the righthand side is the marginal enforcement cost. The …rst-order condition requires h > psM , implying that optimal enforcement entails underdeterrence compared with …rst-best behavior. Some individuals, those for whom
psM
g < h, will commit the harmful act even though it is not socially
warranted. Optimal enforcement trades-o¤ some ine¢ciency in behavior
against savings in enforcement expenses.
With fault-based o¤ences individuals who cause harm are sanctioned
only if they failed to obey some standard of behavior. The legal standard is
in terms of the circumstances under which the harmful act is committed. An
individual’s private bene…t must be above some threshold gb in order for him
to avoid liability; otherwise, he is considered to be at fault. Committing the
7
harmful act is illegal when the circumstances are g < gb, in which case the
individual is subject to a …ne if he is detected; when the circumstances are
g
gb, the harmful act does not constitute an o¤ence. Individuals therefore
commit the act when g
min(ps; gb).
Enforcement costs include the cost of detecting harmful acts and the
additional cost k of assessing circumstances. For a given probability of
detection, the enforcement cost is now
c(p) + kp [1
F (min(ps; gb))]
where the second term is the per capita cost of assessing the circumstances
of the harmful acts committed by undeterred individuals. The optimal policy consists in choosing the …ne, the probability of detection and the legal
standard so as to maximize
Z g
(g h) f (g) dg
c(p)
kp [1
min(ps;b
g)
F (min(ps; gb))] :
The maximum sanction principle still applies and it is easily seen that
an optimal policy requires gb
psM , otherwise enforcement costs could be
reduced with no detrimental e¤ect on deterrence. An interior solution yields
the …rst-order condition
(h + pk
psM )
dF (psM )
= c0 (p) + k [1
dp
F (psM )] :
(3)
Optimal enforcement may now entail either underdeterrence or overdeterrence compared with …rst-best behavior. Overdeterrence would reduce the
frequency of harmful acts and therefore the cost of ascertaining circumstances. As with strict liability o¤ences, there is a trade-o¤ between enforcement costs and some distortion of behavior.
If assessing circumstances involves no additional cost (that is, k = 0),
enforcement costs are the same under fault-based and strict liability o¤ences.
Condition (3) reduces to (2) and welfare is therefore the same under either
8
legal regime. Strict liability and fault-based o¤ences are then equally e¢cient. When k > 0 the optimal legal regime is strict liability. Thus, when
both the legal regime and the enforcement policy are optimally chosen, welfare is maximized by strict liability o¤ences unless assessing fault is costless,
in which case the legal regime does not matter. Moreover, in the optimal
policy individuals are underdeterred to some extent.
Another observation is that, under a fault regime, any standard gb
psM
yields the level of deterrence psM . In other words, the legal standard is
irrelevant. A …nal observation is that a standard above the upper bound of
g) is equivalent to strict liability because committing
possible gains (i.e., gb
the act is then illegal irrespective of possible circumstances.
Social preferences. In the standard model behavior depends on private costs and bene…ts as conventionally de…ned. We now consider normative motivations. There are two types of individuals. A proportion
,
referred to as type t = 1, is intrinsically motivated to behave in a socially
responsible manner. Such individuals are “good citizens” with moral predispositions. The other group, referred to as type t = 0, has no such predispositions. However, prosocial predispositions are socially valued and those
who are thought to be good citizens earn social esteem or status.
The utility of a type-t individual is
ut = w
t max(e
e ; 0) +
;
t = 0; 1:
(4)
The …rst term, w, is net “material” payo¤ as in the standard model. In
the middle term, the parameter
t
is the disutility (“guilt”) su¤ered when
one causes external harm while deviating from the socially responsible behavior e . Misbehavior occurs when e = 1 and e = 0. For the good citizens,
1
> 0 and is su¢ciently large to intrinsically motivate the individual5 ; for
the bad citizen,
5
It su¢ces that
0
1
= 0 and the middle term vanishes. As de…ned here, the
h, i.e., the good citizen “internalizes” the harm he causes.
9
social (or moral) norm of conduct is what everyone should be doing given
the circumstances, which amounts to a simple version of Kant’s categorical
imperative (see Brekke et al. 2003).
The third term in (4) is the utility from one’s social image.
parameter and
is a positive
is society’s belief about the individual’s type. The belief
will depend on information concerning the individual, i.e.,
equals the con-
ditional expectation E (t j I) where I denotes publicly available information.
Given our de…nition of types, the conditional expectation is simply the posterior probability that the individual is a good citizen. All individuals care
equally about social approval;
may be interpreted as the utility of being
perceived as a good citizen, given that the utility of being perceived as a bad
citizen is normalized to zero. The parameter captures both the importance
individuals attach to social approval and the importance (“social pressure”)
society ascribes to being a good citizen in the case at hand. Both
proportion
and the
of good citizens re‡ect the salience of the social norm with re-
spect to the situation (and therefore possible acts) considered. For instance,
when the harmful act is widely viewed as particularly reprehensible,
will
be large and presumably so will be .
It is useful to re‡ect on the assumptions made so far. Consider the
possibility of a multiplicity of moral types
t
0, as in De¤ains and Fluet
(2013). Di¤erent individuals then trade-o¤ di¤erently the moral disutility
of acting bad against material payo¤s. The basic logic of our analysis would
nevertheless remain the same. Similarly the importance of image concerns
could di¤er between individuals, i.e., they have di¤erent ’s. As long as the
’s are positive, the basic logic would still be una¤ected. Obvioulsy, if the
bad citizens in our two-type set-up were characterized by
= 0, we would
be back to the standard enforcement model with respect to regulating their
behavior (the law being super‡uous for the good citizen). To push things
further, it could be that the bad citizen has
< 0, i.e., he enjoys being
seen as bad; for instance, his reference group consists only of bad citizens.
10
Image concerns would then have antisocial e¤ects and much of the results
of our analysis would need to be reversed. Rather than seeking to harness
image concerns, optimal legal design should seek to mute signalling e¤ects;
strict liability o¤ences would then tend to perform better. Our assumptions
disregard such possibilities. In e¤ect, they describe a cohesive society with
commonly shared notions of what is good, although some individuals lack
inner moral strength.6
Welfare is de…ned in the usual way as the sum of utility over all individuals,
W =
Z
g
[(1
)u0 (g) + u1 (g)] f (g) dg
(5)
0
where ut (g) is the utility (or expected utility) of a type-t individual in the
circumstance g.
Before proceeding, we show that …rst-best behavior in the present set-up
is the same as in the standard model without social preferences. Assume that
individuals can both cause harm or su¤er harm caused by others. Consider
an omniscient regulator who can directly impose the action pro…le e(g),
g 2 [0; g]. The average net material payo¤ is then
w = w0 +
Z
g
e(g) (g
h) f (g) dg:
(6)
0
where w0 is initial per capita wealth. Let the action pro…le eb(g) be welfare
maximizing and suppose that the regulator has the option of either publicizing or preventing any information about the individuals’ types. If an
optimum entails that no information is disclosed, then eb(g) maximizes W
subject to the resource constraint (6), given that beliefs satisfy
=
where
is the prior belief about types. This implies eb(g) = e (g) as de…ned in (1).
6
In the terminology of social network analysis with one’s reference group consisting
of one’s “neighbors”, we are assuming an integrated social network in the sense that the
distribution of types among neighbors re‡ects the population distribution (see Bramoullé
et al. 2012).
11
Combining (4) and (5), the …rst-best welfare then equals
W = w0 +
Z
g
(g
h) f (g) dg +
:
(7)
h
The action pro…le e (g) would also be optimal when full or imperfect
information about types is disclosed. First, because the omniscient regulator
is able to independently control the ‡ow of information, there would be no
reason for him to distort behavior from the wealth maximizing action pro…le.
Secondly, welfare would also be as in (7) because reputational bene…ts and
losses simply cancel out.7
O¤ences and labeling. Society at large is assumed not to be able to
directly observe the circumstances faced by an individual nor his behavior.
The assumption prevents social pressure from bearing directly on individuals
independently of the legal system. Otherwise one’s type could be inferred
directly from one’s behavior. When
is large enough there would then
be situations where the legal system plays no useful role. Direct informal
reputational sanctions would su¢ce to induce socially appropriate behavior.
Public enforcers can detect harmful acts and can ascertain the circumstances; that is, they are able to enforce the law when o¤ences are faultbased. Legal proceedings against o¤enders constitute public information
from which society at large draws inferences about the individuals’ type.
For simplicity, we assume that the only information publicly available about
an individual is either G for “guilty”, in which case the individual is known
to have been found guilty of an o¤ence, or N for “no news”. The latter
means that either the individual did not commit an o¤ence or that he did
but was not convicted. The publicly available information a¤ecting one’s
social image is therefore the binary signal I 2 fN; Gg. Society’s belief
about an individual will then be either tN = E(t j N ) or tG = E(t j G).
7
The result follows from the law of iterated expectations and the linearity of reputational utility in the beliefs about one’s type, that is, E(E(t j I)) = E(t) = .
12
The signi…cance of the signal depends on what the events “no news” and
“guilty” reveal about one’s type in the social equilibrium. This will depend
on the legal regime, namely whether o¤ences are strict or fault-based, the
legal standard in the latter case, and on the enforcement policy. Generally
speaking, the event “guilty” will be detrimental to one’s reputation. Other
things equal, individuals wish to avoid being labeled as o¤enders.
We have stressed social signaling which requires that convictions constitute public information. In practice convictions often receive little publicity.
However, as in Bénabou and Tirole (2006), our framework can also be reinterpreted in terms of self-signaling. A simple formulation is Bodner and
Prelec’s (2003) dual-self model. In the latter, an individual’s total utility is
the sum of the “outcome utility” from choosing a particular course of action,
which depends on one’s fuzzily known true inner predispositions, and of a
“diagnostic utility” whereby an individual draws inferences about his true
self from information about his past behavior. For example, one may occasionally exceed the speed limit in a school zone or evade tax, but would feel
shame from being labeled an o¤ender even if convictions are not publicized.8
4
Equilibrium under a Given Regime
This section describes the equilibria under given legal regimes and enforcement policies. A perfect Bayesian equilibrium is characterized by the individuals’ action pro…les and the beliefs about individuals’ type conditional on
the “guilty” and “no news” events. The legal regime is de…ned by the standard of fault when committing the harmful act. The regime is fault-based if
the standard is less than the upper bound of possible gains, otherwise liability is strict. The enforcement policy is de…ned by the sanction for unlawful
conduct and the probability of detecting violations.
8
See McAdams and Rasmusen (2007) on the distinction between guilt, social disesteem,
and shame.
13
We proceed in three steps. First we derive the action pro…les taking as
given the posterior beliefs conditional on the “guilty” and “no news” events.
Next we derive these beliefs as a function of action pro…les. Finally we solve
for the equilibrium wherein action pro…les and beliefs are consistent with
one another.
Incentives. Denote the sanctioning rule by (g; gb) where (g; gb) = 1 if
g < gb and is otherwise zero. The expected utility of a type-t individual in
the circumstance g is
ut = w + e [g
+
p (g; gb)s]
t max(e
pe (g; gb)tG + (1
e (g); 0)
pe (g; gb)) tN ;
e 2 f0; 1g; t 2 f0; 1g:
The …rst two terms comprise material payo¤ as conventionally de…ned.
The …rst term, w, is the part of the individual’s wealth that he takes as given.
This consist of initial wealth minus the average harm caused by others plus
the per capita tax to …nance the enforcement policy (expenditures minus
…nes collected). The second term is the expected net material payo¤ from
committing or not committing the harmful act. The third term is the moral
disutility from committing the harmful act when it is socially unwarranted.
The fourth term is the expected reputational utility. If the individual does
not commit the act (i.e., e = 0) or if he would not be legally at fault when
he does (i.e., (g; gb) = 0), the belief about his type will be tN for sure,
the posterior probability that he is a good citizen given “no news”. If he
unlawfully commits the act, he is detected with probability p and the belief
about his type is then tG , the posterior probability conditional on “guilty”.
If he is not detected, the belief is again tN . These beliefs are determined at
equilibrium but are taken as given by the individual.
If the harmful act is not committed, utility is w + tN for either type. If
it is committed and is lawful, that is g
gb, the utility of the nonprosocial
is w + g + tN . Hence it will then be committed. In circumstances where
14
the act is unlawful, expected utility is
ps) + (ptG + (1
w + (g
and the act is then committed if g
p(s +
p)tN )
), where
tN
tG will
be referred to as the legal stigma, i.e., the reputational loss from being
convicted. The term ps is the standard material incentive to comply with
the law, the term p
is the reputational motive. Altogether a nonprosocial
commits the harmful act when
g
min[b
g ; p(s +
)]
g0 ;
(8)
where g0 is short-hand for the private gain threshold of nonprosocial individuals. In turn the threshold determines the proportion F (g0 ) of nonprosocial
who do not commit the harmful act.
Good citizens are also motivated by legal sanctions and reputational concerns. In addition, their behavior re‡ects an intrinsic concern for complying
with the social (as opposed to the legal ) norm conduct. Given
1
su¢ciently
large, a good citizen never commits the harmful act in circumstances g < h.
When g
h, the harmful act entails no guilt and the good citizen then be-
haves the same as the nonprosocial. The harmful act is therefore committed
if
g
max(h; g0 )
g1
(9)
where g1 is the gain threshold for good citizens. The proportion of good citizens who do not commit the harmful act is F (g1 ). The following summarizes
the preceding discussion.
Lemma 1 g0
gb and g1 = max(h; g0 ).
We shall say that type-t individuals are underdeterred (resp. overdeterred) when the equilibrium threshold gt is less (resp. greater) than the
…rst best h. Whether individuals comply with the law is di¤erent. As
15
noted, the legal standard may di¤er from the …rst best (and social norm).
A consequence of Lemma 1 is therefore that, if there is some overdeterrence
(which requires gb > h), then all individuals are equally overdeterred. Oth-
erwise they either all e¢ciently behave or the good citizens do while bad
citizens are underdeterred. Moreover, bad citizens never overcomply with
the law but good citizens might (when gb < h).
Beliefs. The conditions (8) and (9) de…ne the best response functions of
individuals of either type given the behavior of others. How others behave
a¤ects the payo¤s from one’s actions through its e¤ect on the social signi…cance of the “guilty-no news” events, as captured by the beliefs tG and tN .
The posterior beliefs are obtained from Bayes’ rule given the frequency of
convictions among good and bad citizens. From Lemma 1, g1 is a function
of g0 . Hence posterior beliefs and therefore the legal stigma can be written
as a function of g0 .
Lemma 2 If gb h,
and is decreasing in g0 down to
= when
g0 = gb. If gb > h and g0 < g1 = h,
> 0 and is decreasing in g0 . If gb > h
and g0 = g1 h, = 0.
Unless both types behave the same, bad citizens are more likely to commit the harmful act. Therefore they are more likely to be convicted, implying
that the event “guilty” is bad news concerning the individual’s type compared to “no news”. When the legal standard satis…es gb
h, good citizens
are never found guilty. A conviction then reveals perfectly that the individual is nonprosocial, so that tG = 0 and
= tN . The more the nonprosocial
behave like good citizens, the smaller tN . When everyone behaves the same,
the event “no news” is uninformative because it occurs with certainty, so
the posterior probability then equals the prior
that an individual is a good
citizen.9 When gb > h, as would be the case with a strict liability o¤ence,
both good and bad citizens will at times be convicted, hence tG > 0. As
9
=
is the disutility from being perceived as a bad rather than an average citizen.
16
long as violating the law is more likely for bad citizens, tN > tG and the
legal stigma is positive.10 When both types behave the same, the events
“guilty” and “no news” are uninformative and posterior beliefs equal the
prior in either case. The legal stigma then vanishes.
∆
∆ B ( g0 )
∆ A ( g0 )
λ
0
h
ĝ B
g0
Fig. 1: Legal stigma curves
Figure 1 provides examples of the legal stigma as a function of the bad
citizens’ threshold under two di¤erent legal regimes. The probability of
detection is the same in both regimes. In case A, the legal standard corresponds to the social norm, gbA = h, so that g0
h. The legal stigma is then
prosocial conform to the social norm (i.e., g0
h). When the non prosocial
bounded below by . In case B, the legal standard is above the social norm,
gbB > h, hence g0
gbB . The legal stigma then vanishes when all the non-
The event “guilty” is then an out-of-equilibrium event with zero probablity, implying that
tG cannot be computed using Bayes’ rule. The legal stigma at equilibrium is obtained
from limg0 "bg = limg0 "bg tN = . This can also be rationalized in terms of Cho and Kreps’
(1987) D1 criterion.
10
Strict liability disregards circumstances. Good citizens will then sometimes e¢ciently
choose not to comply with the law given their knowledge of circumstances. See Shavell
(2012).
17
are only slightly underdeterred, the legal stigma under regime A is therefore larger than under regime B. As depicted, the curves intersect. This
need not occur but it is a possibility when the nonprosocial are su¢ciently
underdeterred. We discuss this further in Section 6.
Equilibrium. An equilibrium consists of private gain thresholds and of
a legal stigma that are mutually consistent.
Proposition 1 Let the legal regime and enforcement policy satisfy gb ps.
There is a unique equilibrium with g0 g1 .
(i) If ps h, then g0 = g1 = ps.
(ii) If ps < gb h, then g1 = h, g0 2 (ps; gb] and is increasing in p and s so
long as p(s + ) < gb, otherwise g0 = gb; in either case, g0 is increasing in
gb.
(iii) If ps < h < gb, then g1 = h, g0 2 (ps; h) and is increasing in p and s, it
may be increasing or decreasing in gb.
Legal design matters for incentives only when ps < h. The Figures 2
to 4 illustrate di¤erent equilibria for this case. Good citizens then conform
to the social norm. In the …gures,
(g0 ) is the legal stigma as a function
of the bad citizens’ threshold under a given legal regime and enforcement
policy; g0 ( ) is their threshold as a function of the legal stigma under the
same regime and enforcement policy. The perfect Bayesian equilibrium is
the intersection of the two curves (at point E).
Figure 2 compares the equilibria under two di¤erent legal standards satisfying gb < h. With the standard gbA the equilibrium is at EA , a corner equi-
librium where everyone complies with the law. With the standard gbB > gbA ,
we have an interior equilibrium at EB . In either case, deterrence increases
with a strengthening of the legal standard because this shifts the stigma
curve to the right (so long as gb < h). The intuition is that strengthening
the standard increases the signi…cance of the “no news” event.
18
∆
g 0B (∆)
g 0A (∆)
∆ B ( g0 )
∆ A ( g0 )
EB
EA
λ
ps
0
ĝ A
ĝ B
h
g0
Fig. 2: Equilibria with gb < h
∆
g 0 (∆)
∆( g 0 )
λ
E
h − ps
pβ
ps
0
h
g0
Fig. 3: A corner equilibrium with gb = h
In Figure 3, the standard is the …rst-best gb = h. In the case represented
all individuals comply with the law and therefore are optimally deterred.
This arises when p(s +
)
h. In the …gure, the latter condition holds as a
strict inequality, hence the detection probability could be reduced while still
preserving …rst-best deterrence. Thus, under a fault-based regime, …rst-best
19
deterrence is feasible even though ps < h. Indeed, when p
h, …rst-best
deterrence obtains with purely symbolic convictions with no material legal
sanctions. The …gure illustrates the role of “mild law” as de…ned in Tyran
and Feld (2006), i.e., law backed by nondeterrent sanctions.
∆
∆ A ( g0 )
g 0 (∆)
EA
∆ B ( g0 )
EB
0
ps
h
ĝ A
ĝ B
g0
Fig. 4: Equilibria with gb > h
In Figure 4, gb > h and both types will then sometimes not comply
with the law. First-best deterrence then cannot be achieved with ps < h.
Strengthening the legal standard further may shift the legal stigma curve
upwards or downwards. As before, a stronger standard increases the signi…cance of “no news”. However, it also reduces the signi…cance of the “guilty”
outcome because more good citizens are convicted, so the net e¤ect on deterrence is ambiguous. In the situation represented in Figure 4, weakening
the standard from gbB to gbA shifts the stigma curve upwards, so deterrence
increases.
Increasing the probability of detecting illegal acts increases the signi…-
cance of “no news”, with no e¤ect on the signi…cance of the “guilty” event.11
In the …gures, the legal stigma curves shifts (or rather rotate) upwards. Because o¤enders are now more likely to be convicted, a larger probability of
11
The conditional expectation tG does not depend on p while tN is increasing in p. See
the proof of Lemma 2.
20
detection also shifts the deterrence curve to the right. Thus, greater detection unambiguously increases deterrence, except at corner solutions where
all bad citizens are e¢ciently deterred as in Figure 2. A larger …ne increases
deterrence because it shifts the deterrence curves to the right.12
5
Optimal Legal Regime and Enforcement
Welfare equals the …rst best W as de…ned in (7) minus the loss from socially
ine¢cient behavior and minus the per capita enforcement expenditure:
Z h
Z h
W = W
f(1
)
(h g) f (g) dg +
(h g) f (g) dgg
g0
g1
C(p; g0 ; g1 ; gb)
(10)
where g0 and g1 are equilibrium thresholds as derived in Section 4. The
expression inside the brackets is the loss from ine¢cient behavior; the formulation allows for the possibility of overdeterrence13 . The third term is
the enforcement cost function. When the legal standard gb = g, the regime
is strict liability. Enforcement expenditures then reduce to the cost of detecting harmful acts:
C(p; g0 ; g1 ; g) = c(p):
(11)
When gb < g, o¤ences are fault-based. Enforcement expenditures then in-
clude the cost of assessing the circumstances of the harmful acts that are
detected:
C(p; g0 ; g1 ; gb) = c(p) + pk [1
(1
)F (g0 )
F (g1 )] ;
gb < g:
(12)
Deterrence maximizing legal design. We …rst take the enforcement
policy as given and compare di¤erent legal designs in terms of deterrence.
12
Greater detection has an ambiguous e¤ect on the equilibrium legal stigma. A negative e¤ect may be interpreted as greater legal enforcement partially crowding out informal
motivations; a positive e¤ect re‡ects complementarity between legal enforcement and informal sanctions. By contrast, a larger …ne always reduces the legal stigma.
Rh
Rg
13
When gt > h, gt (h g) f (g) dg = h t (g h) f (g) dg > 0:
21
Proposition 2 When ps < h, deterrence of the nonprosocial is maximized
by either strict liability or the fault-based regime with the standard gb = h.
The result contrasts with the irrelevance of the legal standard in the
standard model without social preferences. Strict liability and fault-based
o¤ences are no longer equivalent because they yield di¤erent legal stigmas,
which in turn a¤ects incentives. Moreover, if deterrence is maximized with
a fault regime, the e¢cient legal standard equals the social norm. When
ps
h, the standard is irrelevant provided that gb
ps. Individuals then
behave as in the standard model and are either e¢ciently deterred or equally
overdeterred.
The intuition for Proposition 2 is that deterrence of the nonprosocial
increases with the legal standard when gb < h. If it can be increased further
still with gb > h, deterrence reaches its maximum at the upper bound gb =
g. For an enforcement policy satisfying ps < h, deterrence is therefore
maximized either with the legal standard gb = h or with the standard gb = g,
where the latter amounts to strict liability.
Legal design and reputational incentives. Figure 5 illustrates why
one regime may perform better. Regime A is fault-based with the standard
gb = h, regime B is strict liability. The …ne and the probability of detection
are the same, hence enforcement need not be optimal.
We compare two situations, L and H, which di¤er in the intensity of
reputational concerns with
L
<
H.
In situation L the deterrence curve
is not very sensitive to beliefs about one’s type and deterrence under either
legal regime is relatively low. As shown, it is greater under strict liability.
Situation H yields the opposite. The social norm has high salience and
individuals are very sensitive to reputational penalties. Deterrence is then
relatively high and is greater with the fault regime.
22
∆
∆ B ( g0 )
∆ A ( g0 )
g 0L (∆)
EBL
g 0H (∆)
E AH
λ
0
ps
h
Figure 5. Stigma e¤ects of legal design when
g0
L
<
H
The foregoing presumes that the stigma curves intersect. As remarked
in Section 3, this need not occur. Convictions are more revealing about
intrinsic predispositions in a fault-based than in a strict liability regime.
However, while the event “guilty” constitutes more unfavorable news about
an individual’s type under the fault regime, the event “no news” is not
more favorable under fault than under strict liability. Because reputational
incentives depend on the di¤erence in beliefs between the “guilty” and “no
news” events, the stigma curves may intersect.
Lemma 3 The stigma curves under strict liability and the fault regime with
the legal standard gb = h intersect at most once and do so if and only if
p>
1
:
1 + (1 2 )F (h)
The condition (13) in the lemma cannot be satis…ed if p
(13)
1=2 or if
1=2. Put di¤erently, the situation depicted in Figure 5 cannot arise
when good citizens constitute a majority or when a majority of harmful
acts are undetected. Given ps < h, a fault regime then always induces
greater deterrence than strict liability.
23
Optimal policies. The optimal legal regime and enforcement policy
must be jointly chosen. Which policy is best depends on the underlying
situation, e.g., the proportion of good citizens, the salience of the social
norm, the likelihood of the circumstances under which harmful acts would
be socially warranted, and the cost of detecting o¤enders and assessing circumstances.
Proposition 3 Under an optimal legal regime and enforcement policy, the
…ne is maximal and the probability of detection satis…es psM < h.
(i) If liability is fault-based, the legal standard is gb = h, the probability of
detection satis…es p(sM + )
h and the nonprosocial are underdeterred
or e¢ciently deterred; convictions constitute a rare event,
p(1
)(F (h)
1
F (g0 )) < :
2
(14)
(ii) If liability is strict, the nonprosocial are underdeterred.
When ascertaining circumstances is not too costly,
(iii) liability is fault-based if
1=2 or if sM or are su¢ciently large; if
liability is strict, convictions (and therefore o¤ences) constitute a frequent
event,
1
:
(15)
p [1
F (h) (1
)F (g0 )]
2
The left-hand side of (14) is the frequency of convictions under a fault
regime. The left-hand side of (15) is the frequency of convictions under
strict liability.14
The maximum sanction principle still holds for the usual reason: a larger
…ne allows the same level of deterrence to be achieved with a smaller probability of detection, thus saving on enforcement costs. By contrast with the
standard model, however, a fault regime may now be optimal even though
assessing fault is costly and …rst-best deterrence may be optimal.
14
Everyone commits the harmful act in circumstances g
prosocial also commit the wrongful act.
24
h; for g in [g0 ; h) the non
Overdeterrence is never optimal. It would require psM > h, in which
case reputational incentives vanish and strict liability does as well as the
fault regime and strictly better if k > 0. But then this is dominated by
strict liability with psM = h which in turn is dominated by strict liability with some degree of underdeterrence and possibly also, if k is not too
large, by the fault regime with either …rst-best deterrence or some degree of
underdeterrence.
∆
g 0B (∆)
∆ A ( g0 )
g 0A (∆)
∆ B ( g0 )
EB
λ
0
EA
p A sMA
pB sMB
h
g0
Fig. 6: Possible optima under a fault regime
In Figure 6, the optimal regime is fault-based when the maximal …ne is
sA
M . As shown, the outcome is the corner equilibrium EA : The probability
of detection is then pA such that pA (sA
M+
) = h and enforcement satis…es
the corner condition
pA kf (h)
dg0
dp
c0 (pA ) + k [1
F (h)] :
(16)
p=pA
The right-hand side is the increase in detection and fault assessment costs
from a marginal increase in the probability of detection. The left-hand side
is the resulting savings in fault assessment costs due to a marginal increase
in deterrence up to g0 = h. The derivative in (16) is a left derivative; the
25
right derivative is zero because increasing detection slightly beyond pA has
no e¤ect on deterrence, as is obvious from Figure 6. Note that a corner
solution as in (16) cannot arise if ascertaining fault is costless, i.e., k = 0.
The equilibrium at EB illustrates an interior optimum where the maximum …ne is smaller and is capped at sB
M . The optimal probability of detection is then pB such that pB (sB
M +
) < h, hence the nonprosocial are
underdeterred. The marginal social bene…t from greater detection is smaller
than in case A because of the smaller …ne. The …rst-order condition is now
(h + pB k
g0 )f (g0 )
dg0
dp
= c0 (pB ) + k [1
p=pB
(1
)F (g0 )
F (h)]
(17)
Whether the optimum is interior or at a corner, fault-based o¤ences may
do better than strict liability even though assessing fault is costly because of
the larger legal stigma attached to convictions. The condition (14) in Proposition 3 is then necessary. If it did not hold deterrence could be increased
by switching to strict liability under the same enforcement policy, as this
would then yield a larger stigma (see the proof). Because this would also
save on the fault assessment costs, strict liability would be unambiguously
better.
Part (iii) of the proposition provides su¢cient conditions for a faultregime to be optimal when assessing fault is not too costly. The condition
that good citizens are su¢ciently numerous follows directly from Lemma 3.
Even when good citizens are not a majority, fault-based o¤ences do better
when either the maximum permissible …ne or image concerns are su¢ciently
large. In either case, appropriate deterrence (including …rst-best deterrence)
can be achieved with a relatively small probability of detection, which ensures that the fault regime is deterrence maximizing. Condition (15) in
Proposition 3 requires p > 1=2 and is necessary for strict liability to be
optimal when assessing fault is not too costly. If the condition did not
hold, switching to fault-based o¤ences would increase deterrence under the
26
same enforcement policy. The condition need not hold when ascertaining
circumstances imposes signi…cant costs. The optimality of strict liability
then follows solely from the fact that assessing fault is too costly.
6
Costly Sanctions and Stigmatization
We consider two extensions of the foregoing analysis. First, we inquire
how the optimal policies di¤er when enforcement relies on nonmonetary
sanctions rather than …nes. Next we relax the assumption that reputational
consequences only serve to motivate and examine the possibility that they
also entail a social cost.
Nonmonetary sanctions. We take imprisonment as an example but
the results would carry over to other forms of nonmonetary sanctions such as
community service or suspension of a licence. Let s now denote the length
of prison sentence, with sM as the maximum allowable. The disutility is
assumed to be proportional to the sentence. While a …ne is a pure transfer
involving no social costs, imprisonment is a net loss in the utilitarian calculus. In addition society may bear a resource cost which we represent by qs
where q is the administrative cost per unit of sentence. Nonmonetary sanctions are in practice rarely imposed for strict liability o¤ences. Even with
fault-based o¤ences, they make sense only because they extend the range
of sanctions, given that e¤ective …nes are capped due to the individuals’
limited wealth.
Consider …rst the standard framework without social preferences. Compared with the formulation in Section 3, enforcement costs are now augmented by the addition of
Z
g
b
p(s + qs)f (g) dg;
min(ps;b
g)
the per capita costs of the sanctions imposed on convicted o¤enders. Whether
the regime is strict liability or fault-based, the optimal policy is again to set
27
the sanction at the maximum permissible level.15 Under strict liability and
by contrast with the case of …nes, the optimal probability of detection may
now entail overdeterrence relative to …rst-best behavior. The possibility
arises because increasing deterrence may reduce prison costs: while o¤enders are more likely to be sanctioned, there will also be a smaller number of
them. Under a fault regime, the optimal legal standard satis…es gb = psM
and everyone then complies with the law (see Shavell 1987). Undeterred
individuals should not be found to be at fault even though they behave inef…ciently from a social point of view, otherwise unnecessary sanction costs are
incurred. When sanctions are socially costly, the advantage of fault-based
liability is therefore to rely on the threat of sanctions while avoiding the cost
of actually imposing them.
When assessing fault imposes no additional cost, a fault-based regime
is clearly preferable. Indeed, fault is preferable if k < (1 + q)sM , i.e., the
cost of assessing fault is smaller than the social cost of the nonmonetary
sanction. With gb = psM , deterrence under a fault regime is the same as
under strict liability with the enforcement policy psM . Enforcement costs
are
c(p) + kp[1
F (psM )] < c(p) + (1 + q)sM p[1
F (psM )]
where the left-hand side refers to the fault regime and the right-hand side to
strict liability. In an optimal fault regime there may also be overdeterrence
because increasing deterrence reduces fault assessment costs.
We now turn to the the model with social preferences. The properties
of the equilibria derived in Section 4 remain the same. The only change is
15
For any given level of deterrence ps, detection costs are reduced if s is raised and p
is reduced proportionnaly, with no e¤ect on sanction costs. One could also consider a
combination of …nes and imprisonment. See Polinsky and Shavell (2007).
28
with respect to the social welfare function which is now
W
= W
(1
Z
f
)f
Z
h
(h
g) f (g) dg + p
g0
h
(h
g) f (g) dg + p
g1
C(p; g0 ; g1 ; gb):
Z
Z
g
b
(s + qs)f (g) dgg
min(g0 ;b
g)
g
b
(s + qs)f (g) dgg
min(g1 ;b
g)
(18)
The terms inside each set of brackets are the social loss from ine¢cient
behavior (again allowing for the possibility of overdeterrence) and the social
cost of sanctions imposed on detected o¤enders. We focus on the characteristics of an optimal fault-based regime.
Proposition 4 With nonmonetary sanctions, when the optimal legal regime
is fault-based the legal standard may be above or below the social norm. When
gb > h, the sanction is maximal, psM = gb and all comply with the law. When
gb h, either the sanction is maximal, p(sM + ) = gb and all comply with
the law; or s
sM , p(s + ) < gb and some of the nonprosocial do not
comply.
Compared with the case of …nes, the di¤erence is that the legal standard
may now di¤er from the underlying social norm. Compared with nonmonetary sanctions in the standard model, the di¤erence is that the sanctions
may actually be imposed. Another di¤erence is that the sanction may be
less than maximum.
When psM = gb > h, everyone complies with the law and is equally
overdeterred. Sanctions are then at the maximum allowable level because
they are never actually imposed. The possibility of a standard gb < h arises
because, while a higher standard would increase deterrence, the number of
convictions would also increase. Speci…cally, @[F (b
g)
F (g0 )]=@b
g > 0; see
Figure 2. This would increase welfare when sanctions consist of …nes, but
with costly sanctions more convictions imply that sanction costs increase. At
corner solutions where everyone complies with the law and gb
29
h, sanctions
are again maximal because they serve only as a threat. When not everyone
complies, however, they may be less than maximal.
To see the latter, recall that the equilibrium threshold of the nonprosocial
solves
g0 = p(s +
(g0 ; p));
(19)
where the legal stigma is written as a function of g0 and of the probability of detection. For a given level of deterrence, the trade-o¤ between the
probability of detection and the sanction is
s dp
p ds
where
p
concerns,
=
g0 =ct
s
s+
(20)
p
denotes the partial derivative. When there are no reputational
= 0 and therefore
= 1. This yields the argument in the
standard model, i.e., it is always desirable to increase the sanction and
reduce the probability of detection proportionally. When
> 0 but the
optimal policy entails overdeterrence, the same argument applies because all
individuals are then equally overdeterred, hence the legal stigma vanishes
and
p
= 0. However, when gb
h and the nonprosocial undercomply
with the law, the legal stigma is positive and
p
> 0, implying
< 1.
Increasing the sanction and reducing the probability of detection so as to
keep deterrence constant then reduces detection costs but also increases
sanction costs. The net e¤ect may be to increase costs.
Socially costly stigmatization. Historically one of the main arguments against strict liability o¤ences was the risk of stigmatizing respectable
entrepreneurs.16 Similar arguments have been made in the discussions accompanying the recent criminal law reforms. One way to capture social
aversion to stigmatization risks is to express reputational utility as a con16
See Paulus (1977) on the debates about “welfare o¤ences” to counter food adulteration
in mid 19th century Britain.
30
cave function of the beliefs about one’s type.17 To facilitate comparison with
our previous formulation, we write the reputational term as v( ) where v
is increasing and strictly concave with v(0) = 0 and v(1) = 1. The overall
utility function of a type-t individual is now
ut = w
t max(e
e ; 0) + v( );
t = 0; 1:
(21)
An omniscient utilitarian regulator would impose the same wealth maximizing action pro…le e (g), but he would not disclose information about the
individuals’ type because reputational gains and losses no longer cancel out.
Hence the …rst-best welfare is
W = w0 +
Z
g
(g
h) f (g) dg + v( ):
(22)
h
All of the results of Section 4 continue to hold provided the legal stigma
is rewritten as
= v(tN )
v(tG ). Assuming that enforcement relies on
…nes, welfare is now
W =W
f(1
)
Z
h
(h
g) f (g) dg +
g0
Z
h
(h
g) f (g) dgg
g1
[v( )
v1
(1
)v 0 ]
C(p; g0 ; g1 ; gb)
(23)
where v t is the average reputational utility of a type-t individual,
v t = p max[F (b
g ) F (gt ); 0]v(tG )+f1 p max[F (b
g ) F (gt ); 0]gv(tN );
t = 0; 1:
(24)
In equation (23) the term inside the curly brackets is the loss from inef…cient behavior. The third term is the deadweight loss from stigmatization.
In the …rst best, reputational utility is
v( ) for all individuals. Under a
given legal regime and enforcement policy, the average reputational utility
is equal to v where
v
(1
)v 0 + v 1 :
17
A similar approach has been used in models of self-signalling, see Köszegi (2006) and
Dal Bó and Terviö (2013).
31
Because v is concave, v
v( ) with strict inequality unless everyone behaves
the same. Social aversion to stigmatization therefore introduces a trade-o¤
between the usefulness of legal stigma for motivating appropriate behavior
and the deadweight loss from stigmatization.18
Proposition 5 Under stigmatization aversion and with sanctions consisting of …nes, the optimal legal regimes and enforcement policies are as in
Proposition 3 except for the legal standard of fault which satis…es gb h.
In a strict liability regime, both good and bad citizens will at times
choose not to comply with the law. When the nonprosocial are underdeterred, tN > tG at equilibrium and therefore v < v( ), meaning that there
is a social loss from legal stigmatization. This loss could be reduced by
increasing the probability of detection because the equilibrium v is increasing in p. Indeed the loss would vanish if the nonprosocial were made to
behave like good citizens with an expected …ne psM
h. However, it is
easily shown that the loss from stigmatization is of the second order when
enforcement is marginally reduced from the level ensuring …rst-best deterrence. Hence, under strict liability, bad citizens are optimally underdeterred
as in Proposition 3.
Under a fault regime, the optimal enforcement policy is similar to part
(i) of Proposition 3 except that the legal standard of fault may now be below
the social norm, i.e., the law is more accommodating than the underlying
social norm. In a corner solution, the deadweight loss from stigmatization
vanishes because everyone complies with the law. The legal standard may
be less than the …rst-best because strengthening the standard reduces the
average reputational utility: a stronger standard increases deterrence, but
some of the nonprosocial then no longer comply with the law. A standard
18
A parallel can be made with Polinsky and Shavell (1979) who discuss the optimal …ne
and enforcement policy when individuals are risk averse with respect to income. Optimal
enforcement may then be non stochastic.
32
gb < h is also possible in an interior solution where some of the nonprosocial
do not comply with the law.
∆
∆ ( g 0 , h)
g 0 (∆)
∆( g 0 , gˆ A )
λ
∆( g 0 , g )
0
psM
g 0′
ĝ A g 0′′
h
g0
Fig. 7: Legal standards and stigmatization
Figure 7 illustrates the advantage of a fault regime together with the
possibility of a standard less than the social norm. Suppose the probability
of detection p is the best enforcement policy under a strict liability regime,
yielding the deterrence curve g0 ( ). We denote the stigma curves under
the same probability of detection as
(g0 ; gb). The curve for strict liability
(g0 ; g) and the equilibrium deterrence level is then g00 . Switching to a
is
fault regime with the standard gb = h would increase deterrence up to g000 .
However, this need not increase welfare because the loss from stigmatization
may be much greater than in the initial situation under strict liability.19
However, as shown in Figure 7, a fault regime does unambiguously better
than strict liability (assuming assessing fault is costless) if the legal standard
19
It is easy to provide numerical examples where, at comparable levels of deterrence,
the social loss from stigmatization is substantially larger under a fault regime than under
strict liability.
33
is weakened to gbA , which corresponds to the stigma curve
(g0 ; gbA ). All
individuals then comply with the law, so there is no stigmatization.
7
Concluding Remarks
Violating the law does not have the same social meaning under strict liability
and fault-based o¤ences. The latter is a stronger signal about one’s character. Fault-based o¤ences will therefore usually perform better in harnessing
reputational concerns for the purpose of motivating socially appropriate behavior. Nevertheless, the result does not always follow because the social
meaning and incentive e¤ects depend on the frequency of convictions.
In many situations, socially unwarranted behavior will be a rare event
because most individuals are socially minded. Convictions may also be rare
because the enforcement policy achieves substantial deterrence. A faultbased regime that seeks to harness reputational incentives should aim at
reducing apparent unlawfulness. Not …nding fault may then be banal, therefore posterior beliefs conditional on “no news” do not di¤er too much from
the prior. But then convictions yield substantial disesteem. By contrast,
when convictions would be a frequent event under a fault regime, o¤ences
are banal. A strict liability regime would then perform better because it
increases the signi…cance of “no news”.
The argument is reminiscent of Bénabou and Tirole’s (2006, 2011) discussion of how acceptable behavior arises from the interplay of “honor” and
“stigma”. High stigma is attached to a behavior that “is just not done”,
only the worst type will do it. Alternatively, when “everyone does it”, the
same behavior carries little stigma. But then “not doing it” yields prestige.
In the case of legal regimes, whether a conviction imposes signi…cant stigma
or whether “no conviction” confers signi…cant honor depends on the underlying situation but also on the legal regime itself together with enforcement
possibilities.
34
Our analysis emphasized the information conveyed by o¤ences under
di¤erent legal regimes given a pre-existing e¢cient social norm. One could
also remark that di¤erent regimes have di¤erent “expressive content”. In
our analysis, the underlying social norm was that individuals should be
socially minded and behave accordingly. Under a fault regime, the norm
can be “expressed” by the duty or obligation with respect to which fault is
de…ned. Indeed, we found that, when enforcement relies on …nes, the optimal
legal standard of fault is identical with the social norm. Strict liability
is fuzzier in this respect. However, when enforcement relies on socially
costly legal sanctions such as imprisonment or when stigmatization entails a
social deadweight loss, the optimal legal norm will generally di¤er from the
underlying social norm. To economize on costly sanctions or enforcement
costs, the standard of fault may be either more lenient or harsher than
the social norm. To mitigate the deadweight loss from stigmatization, the
standard may be more lenient than the social norm.
Strict liability and fault-based o¤ences may di¤er in other ways with
respect to expressive content. In particular, when individuals are imperfectly
informed of the harm they may cause, a legal standard of behavior conveys
information. Its prescriptive content helps socially minded individuals to
coordinate on socially appropriate conduct. Imitative behavior due to social
or self image concerns may then induce some bunching by the nonprosocial
on the socially appropriate behavior.
Appendix A
Proof of Lemma 1. The claim follows directly from (8) and (9).
Proof of Lemma 2. Applying Bayes’ rule,
tN =
1
[1 p max(F (b
g ) F (g1 ); 0)]
p [ max(F (b
g ) F (g1 ); 0) + (1
)(F (b
g)
35
F (g0 ))]
;
(25)
tG =
max(F (b
g ) F (g1 ); 0)
F (g1 ); 0) + (1
)(F (b
g)
max(F (b
g)
F (g0 ))
(26)
where (26) is unde…ned when g0 = g1 = gb.
If g0 < gb
h = g1 , tG = 0 and therefore
= tN =
1
This is decreasing in g0 with
=
1
p(1
=
)(F (b
g)
F (g0 ))
when g0 = gb. If g0
:
(27)
g1 = h < gb,
[1 p(F (b
g ) F (h))]
p [ (F (b
g ) F (h)) + (1
)(F (b
g ) F (g0 ))]
(F (b
g ) F (h))
;
(F (b
g ) F (h)) + (1
)(F (b
g ) F (g0 ))
which is positive and decreasing in g0 with
g1 < gb, (25) and (26) yield tN = tG =
= 0 when g0 = h. If h < g0 =
so that
= 0. For h < g0 = g1 = gb,
we take the limit of the preceding result, so that again
Proof of Proposition 1. Let gb
= 0.
ps. We …rst show uniqueness of the
equilibrium. From Lemma 1 either g0 = g1 > h or g0
2, the …rst case implies
(28)
g1 = h. By Lemma
= 0. Thus, it arises only if ps > h and the
equilibrium is then simply g0 = g1 = ps. A policy with ps
h therefore
yields the second case. The relevant domain for g0 is then the interval
[ps; min(b
g ; h)]. If ps = min(b
g ; h), the equilibrium is trivially g0 = ps, so let
ps < min(b
g ; h). From (8) the equilibrium g0 is a solution to
g0 = min [b
g ; p(s +
where
(g0 ; gb; p))]
(g0 ; gb; p) is de…ned by (27) or (28) for the cases gb
respectively. Equivalently, the equilibrium g0 solves
'(g0 )
min [b
g ; p(s +
(g0 ; gb; p))]
therefore '(ps) > 0. For the case gb
0. Because
h or gb > h
g0 = 0, g0 2 [ps; min(b
g ; h)];
where '(g0 ) is a continuous function. By Lemma 2,
'(b
g)
(29)
h,
(b
g ; gb; p) =
(30)
(ps; gb; p) > 0 and
> 0 and therefore
(g0 ; gb; p) is strictly decreasing in g0 in the relevant
36
domain, so is '(g0 ) and the equilibrium is therefore unique. For the case
gb > h,
(h; gb; p) = 0 and '(h) < 0. Again '(g0 ) is strictly decreasing,
ensuring uniqueness.
(i) The claim for the case ps
h follows directly from the above argu-
ment.
(ii) For ps < gb
(ps; gb]. If p(s +
If p(s +
p(s +
h, the above argument shows that g1 = h and g0 2
)
gb, '(b
g ) = 0 and the equilibrium satis…es g0 = gb.
) < gb, '(b
g ) < 0 and the equilibrium is g0 < gb solving g0 =
(g0 ; gb; p)). Di¤erentiating totally with respect to gb and p yields
p
@g0
=
@b
g
1 p
s+
dg0
=
dp
1
From (27),
g0
is negative while
p
g
b
;
(31)
g0
+p
p g0
and
g
b
p
:
(32)
are positive. Hence (31) and
(32) are both positive. To complete the argument, when p(s +
)
g0 = gb and is then also increasing in gb.
gb,
(iii) For ps < h < gb, the argument is similar except that the solution
now satis…es g0 2 (ps; h). Di¤erentiating (29) totally with respect to gb and
p again yields (31) and (32) but with
g0
and
p
are as before but that of
now de…ned by (28). The signs of
g
b
is now ambiguous (see the proof of
Proposition 2). Thus (32) is positive but the sign of (31) is ambiguous.
How g0 varies with s is derived similarly and is left to the reader.
Proof of Proposition 2. Let g0 (b
g ) denote the equilibrium as derived in
Proposition 1 for some ps < h, so that g0 (b
g)
g1 = h. The deterrence maxi-
mizing legal regime solves maxgb g0 (b
g ). We consider separately the possibility
that the solution satis…es gb
If gb
h or gb > h.
h, the function g0 (b
y ) satis…es part (ii) of Proposition 1 and is
strictly increasing, therefore gb = h. If gb > h, the function g0 (b
g ) satis…es
part (iii) of Proposition 1, hence g0 (b
g ) < h. Either gb = g or gb is an interior
37
solution in (h; g). In the latter case, recalling (31), the solution must satisfy
the …rst-order condition
@g0 (b
g)
@b
g
=
g
b=b
g
p
1
g
g
b(g0 (b
); gb )
= 0;
g ); gb )
g0 (g0 (b
p
where the right-hand-side is as in (31) but with
(33)
de…ned as in (28). The
second-order necessary condition is that
@ 2 g0 (b
g)
2
@b
g
=
g
b=b
g
p
g
g
bg
b(g0 (b
1
); gb )
g ); gb )
g0 (g0 (b
p
(34)
be non positive, where the expression is obtained given that (33) holds and
therefore
g
g
b(g0 (b
); gb ) = 0. Because the denominator in (34) is positive,
the second-order condition requires
g
g
bg
b(g0 (b
where
); gb ) =
= F (b
g)
g
g
bg
b(g0 (b
2p (1
); gb )
0: From (28),
)(F (h) F (g0 (b
g )))
>0
[ (1 p ]2
F (h)
(1
(35)
)F (g0 (b
g )):
Thus, the necessary condition does not hold, implying that the corner solution gb = g is the only possibility.
Proof of Lemma 3. Solve (27) and (28) in the proof of Lemma 2 for the
value of g0 consistent with the same
fault regime with gb = h. This yields
F (g0 ) =
1
2(1
)
(1
under either strict liability or the
2 )F (h)
1
p
p
:
(36)
The equation has a solution F (g0 ) > 0 only if the condition in Lemma 3
holds.
Proof of Proposition 3. We …rst show that ps < h. Suppose to the
contrary that ps
h. Proposition 1 then implies g0 = g1 = ps. If assessing
38
fault is costless the optimal regime is then indi¤erent, otherwise it must be
strict liability. In either case, using (10),
@W
= (1
@p
) (h
g0 ) f (g0 )
@g0
+ (h
@p
g1 ) f (g1 )
@g1
@p
c0 (p):
(37)
For ps > h, @g0 =@p > 0 and @g1 =@p > 0 so that (37) is negative. At ps = h,
the preceding derivatives are discontinuous. Taking the left derivative,
@W
@p
c0 (p) < 0:
=
ps=h
Thus, an optimal policy entails ps < h. By Proposition 1, this implies
g0
g1 = h.
Next we show that s = sM . From (10), under any legal regime, a policy
change that reduces p with no change in g0 is bene…cial because
@W
@p
If gb > h, p and s solve
where
p
p(s +
)
> 0. If gb
=
Cp < 0:
g0 =ct
g0 = p(s +
(g0 ; gb; p)):
(38)
h, either g0 < gb and p and s solve (38); or g0 = gb and
gb. In all of these cases, it is possible to reduce p and increase s
with no change in g0 . Hence the optimal …ne is maximal.
Finally, we now show that, for any enforcement policy with psM < h,
the optimal legal regime is deterrence maximizing. From (10),
@W
= (1
@g0
The sign follows because Cg0
)(h
g0 )f (g0 )
Cg0 > 0:
0; it is zero under strict liability and is
negative if the regime is fault-based and k > 0. Because welfare is strictly
increasing in g0 for all g0
h, Proposition 2 implies that the optimal regime
is either strict liability or the fault regime with gb = h.
(i) Suppose the optimal regime is fault-based. The possibility of …rst-
best deterrence with p(sM +
) = h is discussed in the text. Otherwise,
39
p(sM +
) < h and g0 < h. We now prove (14). If fault-based liability is
optimal for the probability of detection p, we must have
@g0
@b
g
+
p
=
1
g
b=h
g
b(g0 ; h; p)
p
g0 (g0 ; h; p)
0:
(39)
where the expression is a right-derivative and is the same as (33) in the proof
of Proposition 2. Now, the inequality must be strict because, as shown in
the proof of the same proposition,
@ 2 g0
@b
g2
+
> 0;
g
b=h
again a right-derivative. If (39) held as an equality, g0 would be increasing
in gb in a neighborhood of h, implying that gb = h is not deterrence maximiz-
ing. Therefore
g
b(g0 ; h; p)
< 0. From (28), the latter inequality reduces to
condition (14).
(ii) psM < h implies g0
'(g0 )
Recalling that
g1 = h. Under strict liability g0 solves
p(sM +
(h; g; p) = 0, '(h)
(g0 ; g; p))
psM
g0 = 0:
h < 0. Because '(g0 ) is strictly
decreasing, the equilibrium satis…es g0 < h.
(iii) If k = 0, for any p the best regime is the one that maximizes deterrence. By Lemma 3, this is always the fault regime if
or
are su¢ciently large, one can obtain g0 = h with p
p(sM +
) = h, e.g., when sM
necessarily satis…es p
Therefore, for p
2h or
1=2. When sM
1=2 satisfying
2h. An optimal policy then
1=2. Condition (13) in Lemma 3 requires p > 1=2.
1=2, the fault regime dominates strict liability in terms
of deterrence. By continuity, the same argument applies if k is positive but
not too large. To conclude, we prove (15). Using the same argument as in
(i), if the optimal regime is strict liability with gb = g, it must be the case
that
g
b(g0 ; g; p)
0, otherwise deterrence would be maximized with the
fault regime gb = h. From (28), this is equivalent to condition (15).
40
Before proving the next propositions, we derive a result for corner equilibria.
Lemma 4 Let p (sM + ) = gb
h so that g0 (p; gb; sM ) = gb when (p; gb) =
(p ; gb ). Then the right and left derivatives satisfy
@g0
@b
g
@g0
@b
g
@g0
@p
@g0
@p
+
=
(p ;b
g )
p 2 (1
)f (b
g )
;
2
1 + p (1
)f (b
g )
= 1;
(40)
(41)
(p ;b
g )
+
= 0;
(42)
(p ;b
g )
=
(p ;b
g )
sM +
1 + p (1
2
)f (b
g )
Proof: By Proposition 1, when gb < h and p(s +
implies (41) and (42). When p(s +
and (32) respectively where
=
g
b
:
(43)
)
gb, g0 = gb which
) < gb, @g0 =@b
g and @g0 =@p satisfy (31)
satis…es (27). From the latter it is easily seen
that
g0
gb < h;
= p(1
)f (b
g ) and
p
= 0 for g0 = gb
h.
(44)
Substituting in (31) and (32) then yields (40) and (43).
Proof of Proposition 4. We only discuss the case where the optimal
policy does not overdeter.
At a corner solution, p(s +
) = gb
h. Increasing s and reducing p
while preserving the preceding equality has no e¤ect on sanctions (which are
not incurred) but reduces the enforcement cost
c(p) + pk[ (1
F (h)) + (1
)(1
F (b
g )]:
Hence the sanction must be maximal. To see that gb < h is then a possibility,
di¤erentiate welfare in (18) with respect to gb. At a corner solution p(sM +
) = gb < h,
@W
= (1
@b
g
)f (b
g ) (h + kp
gb )
41
@g0
@b
g
p(1 + q)sM
1
@g0
@b
g
:
Substituting from Lemma 4 yields
sign
@W
@b
g
+
= sign fp(1
)(h + kp
gb )f (b
g )
g
b
(1 + q)sM g :
If k is not too large, this is negative for gb su¢ciently close to h.
At an interior solution where g0 < gb, the argument for the possibility
that gb < h is similar. To see that s < sM is then a possibility, set k = 0 for
simplicity. At the policy (p; gb; s),
"
@W
= (1
) (h + p(1 + q)s
@p
@g0
g0 )f (g0 )
@p
(1 + q)s
Z
g
b
f (g) dg
g0
c0 (p)
= 0:
#
(45)
The derivative with respect to s is
"
@g0
@W
= (1
) (h + p(1 + q)s g0 )f (g0 )
@s
@s
p(1 + q)
Z
g
b
#
f (g) dg : (46)
g0
Substituting from (45) in (46) yields
pc0 (p)
@W
=
@s
s
where
(1
)(1
)p(1 + q)
Z
g
b
f (g) dg
(47)
g0
s@g0 =@s
=
p@g0 =@p
s+
s
+p
:
p
The expression follows from (31) and (32); (27) implies
p
Substituting back in (47) yields
"
@W
= sign c0 (p)
(
sign
@s
Z
+p
p )(1
)(1 + q)
> 0 when g0 < gb.
g
b
g0
#
f (g) dg :
Thus, the sign may be negative.
Proof of Proposition 5. We only prove (i) that gb < h is possible when
the optimal regime is fault-based, (ii) that there is underdeterrence when
the optimal regime is strict liability.
42
(i) When gb
h, g0
g1 = h. Setting k = 0 for simplicity, welfare in
(23) reduces to
W =W
(1
)
Z
h
(h
g) f (g) dg
)(1
p(F (b
g)
[v( )
v]
c(p)
g0
where
v = [ + (1
F (g0 ))] v(tN )
(48)
and tN satis…es (27).
Consider the set of corner policies (p; gb) with g0 = gb and
p(sM +
) = gb:
(49)
A necessary condition for a policy in this set to be optimal is
dW
= (1
dp
)(h
gb)f (b
g )(sM +
)
c0 (p) = 0:
(50)
Let (p ; gb ) satisfy (49) and (50) and note that gb < h. For this policy to
be optimal it must also not be bene…cial to move to an interior solution by
marginal independent changes in either p or gb.
The gain from a marginal change in gb while keeping p = p is
@W
= (1
@b
g
)(h
gb )f (b
g )
@g0
@v
+
@b
g
@b
g
(51)
where the notations refer to either the right or left derivatives. From (48)
and (27)
@v
=
@b
g
p (1
)f (b
g ) 1
=
p (1
)f (b
g ) 1
@g0
@b
g
@g0
@b
g
v( ) + v 0 ( )
v( )
v0( ) :
Substituting from (52) in (51) and recalling Lemma 4,
@W
@b
g
= (1
)(h
(p ;b
g )
43
gb )f (b
g )
@tN
@b
g
@g0
> 0;
@b
g
(52)
i.e., reducing gb from gb is not bene…cial.
@W
sign
@b
g
+
= sign p (1
)(h
gb )f (b
g )
(p ;b
g )
Hence, increasing gb from gb is not bene…cial if
p (1
)(h
gb )f (b
g )
v( )
v( )
v0( )
v 0 ( );
:
(53)
where the right-hand side is positive by the concavity of v.
Similarly the gain from a marginal change in p while keeping gb = gb is
@W
= (1
@p
where
)(h
@v
= p (1
@p
Then
@W
@p
gb )f (b
g )
@g0
@v
+
@p
@p
)f (b
g ) v( )
v0( )
c0 (p )
(54)
@g0
:
@p
(55)
+
=
c0 (p ) < 0:
(p ;b
g )
Substituting from (55) and (50) in (54) and again using Lemma 4,
sign
@W
@p
= sign
p (1
)(h
gb )f (b
g ) + v( )
(p ;b
g )
v0( )
:
Thus (53) also ensures that it is not bene…cial to marginally change the
probability of detection.
(ii) Under strict liability with the policy psM = h, the e¤ect of a marginal
decrease in p is given by the left derivative
@W
@p
=
psM =h
@v
@p
c0 (p)
(56)
where
v = p [(1
)(1
+ f1
p [(1
F (g0 ) + (1
)(1
F (h))] v(tG )
F (g0 ) + (1
44
F (h))]g v(tN ):
tN and tG are de…ned in (25) and (26) with gb = g and g0 solves (29). It is
then easily veri…ed that
@v
@p
= 0;
psM =h
hence (56) is negative, implying that p should be reduced from the full
deterrence level.
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