I said it was basically the idea of 'precedents' in law—previous court decisions increase the likelihood the the court will decide the same way in the future. And I pointed out that that probably helps to prevent legal systems from having an 'oscillating' stance on the legality of certain things (that's the 'role' I mentioned earlier, which made it stick for me).

(I think it was pretty close to that—but it was also like 6 years ago.)