Here is the text:
> 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.
So take something like the ACA individual mandate. Does that violate the 10th amendment? Well, it was held to not be a valid exercise of the commerce clause power. But it was held to be a valid exercise of the taxing power. So it cannot violate the 10th amendment, because the taxing power is one of the ones "delegated to the United States by the Constitution." Say the Supreme Court had held it wasn't valid under the taxing power either. Would it violate the 10th amendment? Technically, but the Supreme Court wouldn't invoke the 10th amendment to strike it down, because a law not supported by one of the enumerated powers is invalid anyway.
The 10th amendment, by it's very language, cannot serve as any sort of independent check. If government action passes muster under one of the enumerated powers, it is by definition "delegated to the United States by the Constitution" and cannot violate the 10th amendment. If it doesn't, it's invalid by reason of not being within the government's enumerated powers--no 10th amendment necessary.