Ezra Klein defends an individual healthcare mandate against charges that it's unconstitutional, and what's striking to me is that the argument seems awfully wobbly even if you're on board with a lot of the post–New Deal jurisprudence about the scope of federal power. Sez Ez:
The summary is that you can look at the individual mandate as a tax, which is constitutional, or as a regulation forcing private actors to engage in a certain transaction, much like the minimum wage, which is also constitutional. I've also heard scholars mention auto insurance, which is an obvious analogue, and the Americans With Disabilities Act, which proved that the government can order businesses to install ramps, despite the fact that the constitution doesn't explicitly give the federal government jurisdiction over entryways.
This doesn't seem like the right level of analysis. Some taxes and regulations are within the ambit of federal powers; that doesn't mean anything capable of being so described is. Some things not explicitly and specifically mentioned in Article I are nevertheless necessarily implicit in the enumerated powers; that doesn't mean anything is. Auto insurance seems like a poor analogue because it's a condition of access to government-maintained roadways. Ezra also mentions Massachusetts' individual mandate, which seems rather beside the point in a discussion of the scope of Congress' Article I powers. But bracket that. Even if you think the federal commerce power legitimately extends to legislation like the ADA, there's intuitively a world of difference between saying that a commercial enterprise providing services to the public must provide them in such-and-such a fashion and insisting that private persons have to engage in a specified type of transaction just by dint of being alive. I don't think the best reading of the Commerce Clause encompasses either, but it's not that hard to conceive a reading that extends to the former but not the latter. I stress this just because I don't think you have to be a libertarian or have a very restrictive view of the legitimate scope of federal power to believe there's a genuine question here. The real form of the argument here looks an awful lot like: "Look, we've stretched commerce...between the several states so absurdly already, why are we even pretending it might be found to exclude anything?"