From 1991 to 1995, Brennan was a litigation associate in the Milwaukee office of Foley & Lardner LLP. He later became an assistant district attorney in Milwaukee County, where he first-chaired numerous trials. In 1999, Brennan was appointed by Wisconsin Governor Tommy Thompson to serve as a judge of the Milwaukee County Circuit Court. Taking office in January 2000, he served in this position until November 30, 2008, presiding over almost 300 trials and thousands of motions in criminal and civil cases. During that time, he served as the presiding judge of the civil division of that court. Brennan returned to private practice in 2009 and became a partner at the law firm of Gass Weber Mullins, where he was a trial lawyer in the area of commercial litigation and handles appeals in federal and state courts. He was a partner before being confirmed to the Seventh Circuit. Brennan is a mediator and an AAA certified arbitrator and has published more than 50 articles on federal practice and procedure and criminal sentencing.
Federal judicial service
On August 3, 2017, President Trump nominated Brennan to serve as a United States Circuit Judge of the United States Court of Appeals for the Seventh Circuit, to the seat vacated by Judge Terence T. Evans, who assumed senior status on January 17, 2010. On January 3, 2018, his nomination was returned to the President under Rule XXXI, Paragraph 6 of the United States Senate. Upon the announcement of his nomination, Senator Tammy Baldwin criticized President Trump for bypassing the bipartisan commission composed to vet potential judicial candidates. She withheld her blue slip. However, her Republican counterpart in the Senate, Senator Ron Johnson, praised the nomination. On January 5, 2018, President Donald Trump announced his intent to renominate Brennan to the Seventh Circuit. On January 8, 2018, his renomination was sent to the Senate. On January 24, 2018, a hearing on his nomination was held before the Senate Judiciary Committee. On February 15, 2018, the Senate Judiciary Committee voted on a party line vote to report Brennan's nomination. Democrats strongly objected to the vote, noting that Senator Tammy Baldwin was still withholding her blue slip. On May 9, 2018, the Senate agreed to invoke cloture on his nomination by a vote of 49–47. Brennan's nomination was confirmed on May 10, 2018, by a vote of 49–46. He received his judicial commission on May 11, 2018.
Affiliations and awards
Brennan is the founder of the Milwaukee chapter of the Federalist Society. He has served as a member of the Wisconsin Legislative Council's Special Committee on Crimes against Children. Brennan also chaired the Wisconsin Governor's Judicial Selection Advisory Committee. He received a special commendation from the United States Department of Justice for his service as a member of the National Advisory Committee on Violence Against Women.
