sources of normativity

I'm just beginning Christine Korsgaard's The Sources of Normativity on a recommendation from a legal-philosopher friend. Judging by the introduction, I doubt that it's going to have an account of normativity that much resembles the one that we, insofar as we are critics, and therefore default New Historicists/post-structuralists/etc. assume. Time, we tend to think, is a great worker of normativity, transforming 'is' to 'ought' (pace Hume) across the span of years or centuries, like Euhemerus' princes becoming gods.

The law explicitly allows time this privilege. I'm thinking, in particular, of possession--a factual thing--and property--a normative one. In the Roman law system possession becomes property after a certain period by a process called usucaption, originally instituted as a solution to defective property titles. In the early Republic, one year was required for usucaption of land, two for usucaption of movable real property (slaves, animals, certain farm implements). The same amount of time was required for some types of rights to disappear by non-use (servitudes: as the right to channel water through a neighbor's field, and so forth), and when Justinian lengthened the time needed for usucaption--a practical necessity given imperial expansion--the amount of time required for servitudes to become invalid changed symmetrically. The designated period, then, was the period required for relations to land or goods to become normative, in one way or another.

What I am wondering, then, is whether you can think of any other systems in which time is explicitly considered to create normative relations? I suppose the other example that comes to mind is the philosophy of conservativism, but I rather suspect that's usually an epistemological claim, a claim, that is, that time sorts out which practices are best, not that it in itself legitimates them. Examples? Limit cases?