Gallagher earned his Bachelor of Science from Long Island University in 1989 and his Juris Doctor from New York Law School in 1994.

[2] Gallagher was also a White House Fellow in the U.S. Department of Justice from 2000 to 2001, serving as Counsel to U.S.

President Trump nominated Gallagher to the seat vacated by Judge Joel Harvey Slomsky, who assumed senior status on October 9, 2018.

[3] On October 16, 2019, a hearing on his nomination was held before the Senate Judiciary Committee.

[5] On December 18, 2019, the United States Senate invoked cloture on his nomination by an 82–10 vote.