[4] In 1990, Phillips became a trial attorney at the United States Department of Justice Criminal Division in the Organized Crime & Racketeering Section.

In 2015, after Ronald Machen's resignation as U.S. Attorney, Delegate Eleanor Holmes Norton recommended Phillips for the position.

[4] In December 2015, Phillips announced the closure of a long-running and controversial investigation into former Mayor Vincent C. Gray, who was not charged.

[5][6] During the 2017 dismissal of U.S. attorneys, Phillips was not asked to resign because he had not yet been confirmed and remained acting U.S.

On March 3, 2021, Phillips once again became acting U.S. attorney after being appointed by President Joe Biden.