We present and test empirically a new theory of property and contract rights. Any incentive an autocrat has to respect such rights comes from his interest in future tax collections and national income and increases with his planning horizon. We find a compelling empirical relationship between property and contract rights and an autocrat's time in power. In lasting -- but not in new -- democracies, the same rule of law and individual rights that ensure continued free elections entail extensive property and contract rights. We show that the age of a democratic system is strongly correlated with property and contract rights