After graduating from Father Judge High School in 1982, McCaffery joined the United States Army and served with the First Cavalry Division in Fort Hood, Texas.

[4][5] In November 2022, McCaffery announced his candidacy for a seat on the Pennsylvania Supreme Court left vacant by the death of fellow Democrat Max Baer.

[6] He was endorsed by the state Democratic Party in February 2023,[7] and won the May 2023 primary against fellow Superior Court Judge Deborah Kunselman with 60% of the vote.

[14] Of that total, McCaffery and his allies spent over $13 million,[12] primarily funded by "the state Democratic Party, labor unions, and associations representing trial attorneys.

"[15] On November 7, 2023, he was elected to the Pennsylvania Supreme Court with 53% of the vote;[16] McCaffery's support for abortion rights has been credited as a major factor in his victory.