Richard Posner is the Chief judge of the U.S. Court of Appeals for the Seventh Circuit, a position he has held since 1993, on a court on which he has served since 1981. He is the most prolific federal judge, ever. And while serving on the court of appeals, he has remained among the most prolific legal scholars, ever. If citations measure influence, then Posner is easily the most influential living legal jurist – his 30 books, 330 articles, and 1,680 opinions are by far the most cited, and among the most critiqued.

He is labeled a conservative, and a founder of the law and economics movement. True conservatives might question his allegiance (he is a skeptic of originalism, and a critic of the war on drugs), and his influence in law and economics is more than that of a founder. Posner is the movement’s Henry Ford, not its James Madison: He has put into production a set of pragmatic insights about the relationship between legal rules and outcomes (how will rules affect behavior; how can behavior be better made to �t legal rules), and he has applied the method to an endless range of legal topics – everything from contracts and antitrust to the Constitution’s religion clauses and the behavior of judges.