The web is rightly abuzz with analysis of the Supreme Court’s impending consideration of the US Affordable Care Act, usually known as Obama’s health care bill. Today is the second day of oral arguments. Of the many interesting aspects of the case, the role of precedent stands out. Implicit in much of the discussion on which precedents the Court will follow is that precedent actually matters.  I think it does; others think not.  We shall see. The broader discussion is over whether the Court will be willing to strike such a major law on a weak legal case. The legal issue is whether the Commerce Clause of the U.S. Constitution — 16 words that grant Congress the authority to regulate ‘commerce …