Democracy even if it is a system of self-government, rests on institut
ional commitments. An institutional commitment is a manipulation throu
gh rules of one's set of alternatives. I analyze the nature of institu
tional commitments in general and the role they play in a democracy. A
fter drawing a distinction between committing to a rule and being comm
itted by what a role establishes, three conclusions emerge: a) that re
presentation is a functional commitment, b) that constitutions are com
mitments to rules, and c) that judicial review is not a commitment, bu
t makes credible the commitments embodied in representation and consti
tutions.