Joseph McKenna (August 10, 1843 – November 21, 1926) was an American politician who served in all three branches of the U.S. federal government as a member of the U.S. House of Representatives, as U.S. Attorney General and as an Associate Justice of the Supreme Court.

[2] Born in Philadelphia, Pennsylvania, the son of Irish Catholic immigrants, he attended St. Joseph's College and the Collegiate Institute in Benicia, California.

[5] McKenna was nominated by President McKinley on December 16, 1897, as an associate justice of the Supreme Court of the United States, to succeed Stephen Johnson Field.

[1] Conscious of his limited credentials, McKenna attended Columbia Law School for about a month between his nomination and Senate confirmation to improve his legal education before taking his seat on the Court.

[11] His passionate rebuttal to the denial of "pecuniary benefit" to a wife whose husband had been killed while working on the railroad was among those which brought a change to the Employer Liability Act.

[15] While McKenna was generally quite favorable to federal power, he joined the Court's substantive due process jurisprudence and voted with the majority in 1905's Lochner v. New York, which struck down a state maximum-hours law for bakery workers.