Most people mean powers of government not specifically delegated to the federal government when they talk about "states rights".
Conveniently [there's that word again] ignoring that States are prohibited by the Constitution from infringing upon individual rights.
You say that the Cons prohibits the states from infringing on individual rights. This isn't quite true. The Cons pretty much leaves the states free to deal with civil liberties as they see fit. The prohibitions on the states are found in art 1 sec 10, and as you can see, those prohibitions are pretty thin. It's not that the framers didn't care or anything, it's just that the states were used to dealing with their own issues, and would have certainly had problems if the new G had come along and said, "Here now, we're the new boys in town and you will do this and this with your laws, and that's that."
I said 'most people'. I know better.
Convenience has become an entitlement.