Dan Himmelfarb joined Mayer Brown in 2007, after serving for five years as an Assistant to the US Solicitor General. During that time, he argued 10 cases and filed more than 150 merits and petition-stage briefs in the US Supreme Court. Before working in the Solicitor General's Office, Dan served for five years as an Assistant United States Attorney in the Southern District of New York, where he tried eight cases in district court and argued 10 cases in the US Court of Appeals for the Second Circuit. Before joining the Department of Justice, Dan was in private practice for three years in New York.

Dan received his A.B. magna cum laude from Princeton University and his J.D. from Yale Law School, where he was a senior editor of the Yale Law Journal. Dan clerked for Judge J. Michael Luttig of the US Court of Appeals for the Fourth Circuit and for Justice Clarence Thomas of the US Supreme Court.

Since joining Mayer Brown, Dan has argued a total of 10 cases in seven different appellate courts: the District of Columbia, Second, Fourth, Sixth and Seventh Circuits; the Kentucky Supreme Court; and the Tennessee Court of Appeals. He also represented the petitioner in CSX Transportation, Inc. v. Hensley, 129 S.Ct. 2139 (2009) (per curiam), in which the Supreme Court took the highly unusual step of summarily reversing the decision below, without merits briefing or oral argument. Dan is a co-author of Mayer Brown's Federal Appellate Practice treatise, published by BNA Books in December 2008.