Some of the U.S. Supreme Court’s most significant decisions are those declining to hear a case. Two weeks ago, the Court made such a momentous non-ruling in refusing to hear a lawsuit, Hall v. Sebelius, challenging government policies that deny otherwise eligible retirees their Social Security benefits if they choose not to enroll in Medicare. (I previously wrote about the case, and Cato filed a brief supporting the retirees’ petition for Supreme Court review.)