The selection effect is the major factor in determining which disputes or law-controlled events wind up in litigation, but the effect is even greater as we proceed up the appellate ladder. In its 2007 Term, for example, the United States Supreme Court, which has almost total power to decide which cases it wants to hear, was asked to hear more than nine thousand cases from the federal courts of appeals and from the highest courts of the states, but agreed to take and decide, with full briefing and argument and opinions, only seventy-one. These seventy-one cases were almost all ones in which there was no clear legal answer, and taking these seventy-one as representative of how law works or how rules work would be a major blunder.

Unknown, Frederick Schauer - Thinkin…, loc. 39