And I do think, Justice Kennedy, getting back to the question you asked before, what -- what matters here is whether Congress is choosing a tool that's reasonably adapted to the problem that Congress is confronting. And that may mean that the tool is different from a tool that Congress has chosen to use in the past. That's not something that counts against the provision in a Commerce Clause analysis.
JUSTICE SCALIA: Wait. That's -- it's both "Necessary and Proper." What you just said addresses what's necessary. Yes, has to be reasonably adapted. Necessary does not mean essential, just reasonably adapted. But in addition to being necessary, it has to be proper. And we've held in two cases that something that was reasonably adapted was not proper, because it violated the sovereignty of the States, which was implicit in the constitutional structure.