Hon. Mary Ann C. O’Brien is a judge for the Vicinage 3 Superior Court in Burlington County in New Jersey. She was appointed to the bench by Governor Phil Murphy in 2020.
During her judicial tenure, O’Brien has held an assignment in the Family Division in Burlington County.
At the time of her appointment, she had served as the Burlington County surrogate since being elected in 2016 (2017 to 2020). Before that, O’Brien held the office of Burlington County freeholder, a position to which she was elected in 2014 (2015 to 2017) and 2009 (2010 to 2012).
In addition, she spent time as a member of the Medford Township Council.
O’Brien received a B.A. from Pennsylvania State University in 1980. She went on to complete a J.D. at the University of Dayton School of Law (1983) and an M.B.A. from the University of Dayton (1985).
Over the course of her legal career, O’Brien also practiced as an attorney in the law firm of Crammer, Bishop, Marczyk & O’Brien.
She is registered as a Republican.