His principal teaching and research areas include criminal law and procedure, sentencing, and professional responsibility.

[5] However, as part of a deal between Senate Democrats and Republicans that also paved the way for a vote to confirm Clinton's nomination of Republican Bradley A. Smith to the Federal Election Commission and Federal Circuit nominee Timothy B. Dyk,[6] Lynch was confirmed by the United States Senate on May 24, 2000, by a 63–36 vote,[7] and he received his commission the following day.

[2] As a district court judge, Lynch presided over the perjury trial of rap artist Lil' Kim in 2005.

[8] Judge Lynch is also an active participant in Legal Outreach, a non-for-profit organization in which he mentors inner-city kids in New York.

On April 2, 2009, President Barack Obama nominated Lynch to a seat on the United States Court of Appeals for the Second Circuit vacated by Judge Chester J. Straub, who assumed senior status on July 16, 2008.

[2] Upon signing a full and unconditional pardon for Ross William Ulbricht United States President Donald Trump criticized Lynch’s character and harsh sentencing: