Pierce Butler (March 17, 1866 – November 16, 1939) was an American jurist who served as an associate justice of the Supreme Court of the United States from 1923 until his death in 1939.

When he was nominated for the United States Supreme Court in 1922, Butler was in the process of winning approximately $12,000,000 for the Toronto Street Railway shareholders.

On December 5, 1922, Butler was nominated by President Warren G. Harding as an associate justice of the Supreme Court, to succeed William R.

[6] Although he was Chief Justice William Howard Taft's top choice for the seat, Butler's opposition to "radical" and "disloyal" professors at the University of Minnesota (where he had served on the Board of Regents) made him a controversial Supreme Court nominee.

[1] As an associate justice, Butler vigorously opposed regulation of business and the implementation of welfare programs by the federal government (as unconstitutional).

[5] This earned him a place among the so-called "Four Horsemen," which also included James Clark McReynolds, George Sutherland, and Willis Van Devanter.

He wrote the majority opinion (6–3) in United States v. Schwimmer, in which the Hungarian immigrant's application for citizenship was denied because of her candid refusal to take an oath to "take up arms" for her adopted country.

In Palko v. Connecticut, Butler was the lone dissenter; the rest of the justices believed that a state was not restrained from trying a man a second time for the same crime.

[citation needed] He sided with the majority in Pierce v. Society of Sisters, holding unconstitutional an Oregon state law that prohibited parents from sending their children to private or religious schools.