Social Norms and Legal Design

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.