Well, actually it's perfectly possible for an older patent to be broader than a newer and necessarily narrower patent. That is in fact the goal of writing a val

Well, actually it's perfectly possible for an older patent to be broader than a newer and necessarily narrower patent. That is in fact the goal of writing a valuable patent. Even if only a narrow thing has already been claimed, but the spec enables something broader then only something narrower still can be patented after that publishes... otherwise it is not novel. Of course not all prior art is in patents so any journal publication could also force narrowing of claims. Older patents are almost always broader... if they cover the thing you want at all.