Liam C. Brennan was born in 1967 and raised in the Chicagoland area until his family moved to Ireland, where he attended secondary school. He returned to the United States and earned a Bachelor of Arts degree from the University of Notre Dame in 1989.  Before attending law school, he worked at the Inter-American Foundation in Washington, D.C. and as a volunteer teacher at Cardinal Spellman High School in the Bronx, N.Y.  He then earned his Juris Doctorate from Loyola University Chicago School of Law in 1993.  Brennan’s legal career started with one year as a civil practitioner, followed by four years clerking for Illinois Supreme Court Justice, James D. Heiple, and then 10 years as an Assistant State’s Attorney for DuPage County, where he was promoted to Supervisor of the Child Abuse/Domestic Violence Unit.  During this time, he tried over 60 jury trials and numerous bench trials to verdict.

Judge Brennan was appointed as an Associate Judge for the 18th Judicial Circuit in 2008.  In 2014, he was appointed and subsequently elected to the Circuit Court.  As a trial judge for eleven years, Judge Brennan served in various capacities, including as Presiding Judge of the Felony Division.  Judge Brennan was appointed to the Second District Appellate Court in March 2020. 

Judge Brennan has served on a variety of Supreme Court Committees, including: Vice Chair of the Illinois Judicial College Committee on Probation Education; the Commission on Pretrial Practices; the Pattern Civil Jury Instructions Committee; the Pattern Criminal Jury Instructions Committee; and the Committee for Judicial Education.  He also served as Chair of the Illinois Judicial Benchbook on DUI/Traffic, and as a faculty member for various judicial education classes.

Judge Brennan and his wife have three children.