Brennan is a Springfield native. He obtained his Juris Doctorate degree in 2014 from Saint Louis University School of Law, where he completed an externship with the Department of Veteran’s Affairs Office of Regional Counsel at Jefferson Barracks. He also completed externships with the VA in the District of Columbia, specifically with the Office of General Counsel and Office of Quality, Safety, and Value. During this time, he also served as Editor for the Saint Louis University Law Journal. He was privileged to serve as intern with the Honorable Magistrate Judge Shirley Padmore Mensah in the U.S. District Court for the Eastern District of Missouri.

After graduating from law school Brennan moved back to Springfield and has been practicing with Shannon Grisham and John Pratt since 2015, primarily in the area of Family Law.

In 2018 he participated in The National Family Law Trial Institute in Houston, and received specialized training in Custody, Business Valuation, Direct and Cross-Examination and actual mock court experience.