We are all familiar with the image of the immensely clever judge who discerns the best rule of common law for the case at hand. According to U.S. Supreme Court Justice Antonin Scalia, a judge like this can maneuver through earlier cases to achieve the desired aim--"distinguishing one prior case on his left, straight-arming another one on his right, high-stepping away from another precedent about to tackle him from the rear, until (bravo ) he reaches the goal--good law." But is this common-law mindset, which is appropriate in its place, suitable also in statutory and constitutional...