While at Hofstra Law School, she worked for the New York State Attorney General's Office handling consumer mediation. In addition, she represented clients under a practice agreement for the law school's disabilities clinic. Upon admission to the New York State Bar, Ms. Brennan began her career as an attorney for a major malpractice carrier's in-house counsel representing physicians, osteopaths, podiatrists, hospitals and medical professional corporations in medical malpractice actions. She was responsible for the intake of summonses and complaints and drafting responsive answers and for discovery. She handled court appearances and proceedings in all venues in the New York metropolitan area.