Ian Millhiser has a video of former Ronald Reagan Solicitor General Charles Fried defending the constitutionality of the individual mandate, citing former Chief Justice John Marshall's definition of commerce:
I am quite sure that the health care mandate is constitutional. … My authorities are not recent. They go back to John Marshall, who sat in the Virginia legislature at the time they ratified the Constitution, and who, in 1824, in Gibbons v. Ogden, said, regarding Congress' Commerce power, “what is this power? It is the power to regulate. That is—to proscribe the rule by which commerce is governed.” To my mind, that is the end of the story of the constitutional basis for the mandate.
What's so remarkable is that, as Scott Lemieux points out, Judge Roger Vinson actually cited Marshall in his opinion striking down the Affordable Care Act, which Lemieux writes is like citing "Earl Warren and Thurgood Marshall to argue the Civil Rights Act is unconstitutional." Sen. Orrin Hatch objected to Fried's argument but gave no real reason for doing so beyond simply disagreeing with his reasoning, which prompted Ezra Klein to remark that "the Judiciary Committee's hearing on the constitutionality of HCR shows how weak argument and expertise are when pitted against partisanship."
I think we've already known that, and if we didn't know it, Bush v. Gore should have made that clear. But I think that's the primary lesson behind Vinson's ruling on the ACA. As Orin Kerr noted yesterday, Vinson essentially "used a first principle to trump existing Supreme Court caselaw when that principle may not be consistent with existing caselaw."
Only lawyers really care about "existing case law," because they're trained to be able to decipher it. Most Americans are approaching this from the point of view of their understanding of constitutional first principles. Vinson's ruling was actually about winning an argument outside of court. Liberals win the legal argument easily based on legal precedent; they're losing the political one badly -- as Steve Benen's account of the relative differences in coverage of ACA rulings shows.
Vinson's ruling, for the reasons Kerr identifies, is the definition of "activism," but that term is so selective that it's lost almost all meaning. Conservatives, liberals, and libertarians all agree that good precedents should be upheld and bad ones should be overturned. We all disagree on which ones are bad and which ones are good, but conservatives have been really effective at defining activism in starkly political terms, where "activism" is applied exclusively to decisions that lead to policy outcomes they don't like. Again, that reflects an understanding of the judiciary as a political and politicized institution that liberals have really failed to appreciate, and it's one of the reasons they may lose this fight.