> Congress can't pass laws preventing Congress from passing other laws, except by amending the Constitution. Congress can't amend the Constitution, either. So

> Congress can't pass laws preventing Congress from passing other laws, except by amending the Constitution. Congress can't amend the Constitution, either. So we're left with, essentially, "Congress can undo what Congress can do.". Congress can of course propose amendments to the Constitution, and therefore also propose amendments which repeal previous amendments. In either case, ratification by by the state legislatures is required.