John Marshall Mitnick is an American lawyer who served as General Counsel for the United States Department of Homeland Security.
From 2001 to 2002, he served as a Counsel to the Assistant Attorney General of the Antitrust Division within the United States Department of Justice. From 2002 to 2004, he served as an Associate General Counsel for Science and Technology at the United States Department of Homeland Security. During the presidency of George W. Bush, he served as Deputy Counsel of the Homeland Security Council (2004-2005) and then as Associate Counsel to the President (2005-2007).
He was nominated by President Trump in August 2017 to serve as General Counsel of the United States Department of Homeland Security and was confirmed by the United States Senate by voice vote on February 15, 2018. He was fired as DHS general counsel on September 17, 2019, reportedly because he had resisted illegal policies and actions pushed by White House Senior Advisor Stephen Miller. In 2020 he endorsed Joe Biden’s presidential candidacy, along with multiple other Trump former officials. He also joined over 70 former senior Republican national security officials in issuing a statement, initially released on August 20, 2020, critical of Donald Trump and endorsing Joe Biden.