Prohibitions on punishments in private contracts

In most contemporary economies loan contracts that mandate exclusionary penalties such as imprisonment or other non-pecuniary punishments for defaulting debtors are illegal, despite the fact that in some cases contracting parties might gain by being able to use them. A possible rationale for contracting restrictions of this type is that exclusion imposes negative externalities on individuals not party to the original loan contract. We explore the ability of such externalities to account for these restrictions. We contrast exclusion with enforceable collateral seizure, a widespread feature of developed financial systems. We also consider "behavioral" agents who underestimate their chances of being punished, and show that overconfidence of this type is a less compelling justification for restrictions on exclusionary punishments than is often argued.