After graduating from Yale Law School, he practiced general commercial litigation in New York City for over twenty years. In 1994 President Clinton appointed him U.S. District Judge for the Southern District of New York, and President Bush appointed him to the Second Circuit Court of Appeals in 2001. Before becoming a judge, he was president of the board of the Harlem School of the Arts. Judge Parker held leadership positions with the NAACP Legal Defense and Education Fund Inc. and the Association of the Bar of the City of New York and board memberships at St. Paul's School and the New School for Social Research. He continues to serve on the board of Yale-New Haven Hospital.