Answer by taking a quote from the following article:

Richard Allen Posner (; born January 11, 1939) is an American jurist and economist who was a United States Circuit Judge of the United States Court of Appeals for the Seventh Circuit in Chicago from 1981 until 2017, and is a Senior Lecturer at the University of Chicago Law School. He is a leading figure in the field of law and economics, and was identified by The Journal of Legal Studies as the most cited legal scholar of the 20th century. Posner is known for his scholarly range and for writing on topics outside of his primary field, law.

In Posner's youth and in the 1960s as law clerk to William J. Brennan he was generally counted as a liberal. However, in reaction to some of the perceived excesses of the late 1960s, Posner developed a strongly conservative bent. He encountered Chicago School economists Aaron Director and George Stigler while a professor at Stanford. Posner summarized his views on law and economics in his 1973 book The Economic Analysis of Law.  Today, although generally viewed as to the right in academia, Posner's pragmatism, his qualified moral relativism and moral skepticism, and his affection for the thought of Friedrich Nietzsche set him apart from most American conservatives. As a judge, with the exception of his rulings with respect to the sentencing guidelines and the recording of police actions, Posner's judicial votes have always placed him on the moderate-to-liberal wing of the Republican Party, where he has become more isolated over time. In July 2012, Posner stated, "I've become less conservative since the Republican Party started becoming goofy." Among Posner's judicial influences are the American jurists Oliver Wendell Holmes, Jr. and Learned Hand.  In June 2016, Posner was criticized by right-wing media organizations for a column he wrote for Slate in which he stated, "I see absolutely no value to a judge of spending decades, years, months, weeks, day, hours, minutes, or seconds studying the Constitution, the history of its enactment, its amendments, and its implementation."  He has called his approach to judging pragmatic. "I pay very little attention to legal rules, statutes, constitutional provisions... A case is just a dispute. The first thing you do is ask yourself -- forget about the law -- what is a sensible resolution of this dispute? The next thing...is to see if a recent Supreme Court precedent or some other legal obstacle stood in the way of ruling in favor of that sensible resolution. And the answer is that's actually rarely the case. When you have a Supreme Court case or something similar, they're often extremely easy to get around."

What important decisions has he made?