Custom and treaty. this article applies the literature of law and social norms in a way that suggests
how to bridge the gulf between law and social norms-one that is not as readily apparent
in the domestic context. It recognizes that law, on the one hand, and social norms, on the other,
are alternative and sometimes complementary means of social control or social cooperation.
It thus suggests the utility of comparative institutional analysis'20b etween law and social norms.
Custom is a mechanism for international "legislation" that requires only a degree of consensus,
121 not affirmative unanimity. Given the difficulty of establishing global treaties without significant
holdouts, and given the need to avoid free riders, we might understand the CIL process
as an alternative mechanism for global legislation. A rule of consensus acts as a default rule that
promotes compliance and that increases the bureaucratic costs of "persistent objectors." We
recognize that this type of strategy would raise concerns regarding democratic legitimacy. This
type of legislative technique is not more invasive than majority voting, however, and the "persistent
objector" rule allows states to opt out of rules that raise sufficient concern.