Richard Posner, the pioneering legal scholar and longtime federal appellate judge, died Tuesday at age 87.

The University of Chicago Law School announced his passing Wednesday. Posner served on the U.S. Court of Appeals for the Seventh Circuit from 1981 until his retirement in 2017, writing approximately 3,300 opinions during his tenure.

President Ronald Reagan appointed Posner to the bench. He rose to chief judge of the Seventh Circuit from 1993 to 2000. Colleagues and observers widely regarded him as one of the most influential lower-court judges of his era.

Posner joined the University of Chicago Law School faculty in 1969 and helped establish the field of law and economics. His 1973 book The Economic Analysis of Law remains a foundational text now in its ninth edition. He authored dozens of additional books and hundreds of scholarly articles.

Born in New York City in 1939, Posner graduated from Yale University and Harvard Law School. He clerked for Supreme Court Justice William Brennan before working at the Federal Trade Commission and in the solicitor general's office.

Law School Dean Adam Chilton described Posner as a prolific and endlessly curious giant whose influence on the legal system and the law school cannot be overstated.

Posner was known for his libertarian-leaning views and commitment to applying economic principles to legal questions. His work shaped debates on antitrust, regulation, and common law efficiency for decades.

He is survived by his wife, Charlene Horn, and two children, including son Eric Posner, also a legal scholar at the University of Chicago.