[VikingCoder]

Your "at least in theory" is not true in practice.

The 10th Amendment states:

"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."

And the Supreme Court has ruled that "added nothing to the [Constitution] as originally ratified".

The Commerce Clause lets the federal government get away with just about anything.

[amalcon]

The tenth amendment obviously did add nothing substantive to the Constitution. The Constitution explicitly enumerates the things the various branches of government can do. Explicitly stating that they can't do other things is no more necessary than an explicit inclusion of "No cheating" in the rules of a game.

The commerce clause thing is a separate issue. Wickard v. Filburn had nothing to do with the tenth amendment, as it is based on a (particularly broad) interpretation of one of those enumerated powers.

I am not a lawyer, this is not legal advice, you should hire a lawyer if you are somehow in a situation where this is directly relevant to you.