Dave Kopel describes what the Supreme Court should do when hearing the challenge to ObamaCare:

The Court should re-affirm Gibbons v. Ogden, which followed the original understanding of the interstate commerce clause: “commerce” means mercantile exchange, plus some closely-related subjects, such as navigation. Among the subjects which are not interstate commerce, according to Gibbons, are “health laws of every description.” …

Finally, Congress should explain that the Necessary and Proper clause underscores the unconstitutionality of the mandate. …

Read Kopel’s entire answer here: The Volokh Conspiracy » What Should the Supreme Court do with the Obamacare Case?.