Well, yah, that produces a problem:
...Much of the recent natural law literature in Catholic circles is, in fact, devoted to an attempt to reconcile natural law and natural rights. However carefully this reconciliation may have been, it has made hardly any dent on the popular notion that “rights” are what we define them to be in positive law. Thus they bear the same voluntary mutability as positive law itself.
What's a "right" on Tuesday could be "not a right" on Wednesday, you see. That's how the Mad Hatter would 'splain it; and that's where we are.