Last December, during my oral argument in the medical marijuana case of Gonzales v. Raich, the center chair normally occupied by Chief Justice William Rehnquist was empty. Without the towering, and sometimes glowering, visage of the chief, with his no-nonsense demeanor and questioning, there was a palpable void in the courtroom that day. Now, with his passing, there is a void in the Supreme Court itself. Today we mourn the death of William Rehnquist. One day soon we may mourn the death of his legacy--the jurisprudence of the Rehnquist court. Even before becoming chief justice, often in lonely dissents, it...