From 1991 to 1993, he was a legal assistant at the law firm Cleary Gottlieb Steen & Hamilton, and from 1993 to 1994 he was a waiter at a restaurant in Washington, DC.

He also served as the Republican staff director for the Senate's Caucus on International Narcotics Control,[2] and from 2013 to 2017 Judge Kelly served as Chief Counsel for National Security and Senior Crime Counsel to U.S. Senate Judiciary Committee Chairman Charles E.

[1] Kelly presided over English v. Trump, a lawsuit related to the Federal Vacancies Reform Act and the successor to the Director of the Consumer Financial Protection Bureau, Richard Cordray, who had resigned in November 2017 to kick off a run for Governor of Ohio.

Kelly declined to issue a temporary restraining order and held that Mulvaney could remain as acting director.

CNN filed a lawsuit in order to challenge this decision and alleged this violated Acosta's first and fifth amendment rights.

[9] On December 28, 2021, Kelly refused to dismiss an indictment against four members of the Proud Boys who were charged with conspiracy in the 2021 United States Capitol attack.