http://balkin.blogspot.com/2012/03/limiting-principle.html
The real problem here seems to me to be this: the Supreme Court justices are lawyers. And the kinds of question being asked in this instance require a deep knowledge of economics.
The healthcare market is not the same kind of thing as a market for broccoli, cell phones or cars. If they knew this, they wouldn't have asked the questions that they did.
http://www.who.int/bulletin/volumes/82/2/PHCBP.pdf