After his clerkship, he joined the firm Cohen, Gettings & Dunham, P.C, where he was an associate from 1996 to 2000 and a partner from 2000 to 2002.

[3] In 2007, he argued the case Kimbrough v. United States before the U.S. Supreme Court, in which the Court ruled district judges have discretion to depart from Federal Sentencing Guidelines in cases involving crack cocaine.

[7] In April 2021, Senators Mark Warner and Tim Kaine recommended Nachmanoff to be a United States District Judge for the Eastern District of Virginia to the seat vacated by Judge Liam O'Grady.

President Biden nominated Nachmanoff to the seat vacated by Judge Anthony Trenga, who assumed senior status on June 1, 2021.

[11] On October 26, 2021, the United States Senate invoked cloture on his nomination by a 51–46 vote.