David Gannon was born and raised in Brooklyn, New York. He attended Flatbush High School. He attended Brooklyn College in Brooklyn, NY where he obtained his B.A. in Economics and graduated Magna Cum Laude in 1989. He was also a member of Phi Beta Kappa. Mr. Gannon obtained his J.D. in 1992 from Syracuse University School of Law, where he was an Associate Editor of Law Review from 1990-1992.
In 1992, Mr. Gannon began his career as a trial lawyer as an Assistant District Attorney in Brooklyn, New York. As an Assistant District Attorney, Mr. Gannon investigated thousands of criminal cases, presented hundreds of cases to the New York State Grand Jury and successfully obtained jury verdicts on behalf of the People of the State of New York, including crime victims. Mr. Gannon was promoted to Senior Assistant District Attorney where he focused on prosecuting felonies, including shootings, robberies, and attempted homicides.
After leaving the District Attorney's Office in 1996, Mr. Gannon began his career in private practice at a prominent New York City law firm specializing in medical malpractice litigation. During that time, Mr. Gannon represented hospitals and physicians against claims of medical malpractice.
In 1999, Mr. Gannon joined this firm, where to this day, he has tried numerous medical malpractice cases to verdict and has obtained favorable outcomes in a variety of cases, including cases involving allegations of infant brain damage. In January 2007, Mr. Gannon became a partner of the firm.