Cullen is a 1996 graduate of
Collegiate School in Richmond, Virginia. He received his
Bachelor of Arts from
Furman University cum laude in 2000. He received his
Juris Doctor from the
William & Mary School of Law in 2004, where he was inducted into the
Order of the Coif. He was a
law clerk to Judge
Robert E. Payne of the
United States District Court for the Eastern District of Virginia from 2004 to 2005 and for Judge
Roger Gregory of the
United States Court of Appeals for the Fourth Circuit from 2005 to 2006. Cullen served as an
assistant United States attorney for the
Western District of North Carolina from 2006 to 2010 and for the
Western District of Virginia from 2010 to 2013, where he was Deputy Criminal Chief. Before becoming U.S. Attorney, he was a principal/partner at Woods Rogers PLC in
Roanoke, Virginia, from 2013 to 2018, representing clients in complex civil and criminal litigation.
U.S. Attorney Cullen was recommended as a candidate for
United States attorney by Virginia
Senators Mark Warner and
Tim Kaine. On March 22, 2018, his nomination was reported out of committee by
voice vote. He was confirmed by
voice vote later the same day. He was sworn in on March 30, 2018. As U.S. Attorney, Cullen directed the federal response to the deadly "Unite the Right" rally in Charlottesville, Virginia, successfully prosecuting several white supremacists who committed hate crimes and other acts of violence. His tenure as U.S. Attorney ended on September 15, 2020, when he became a federal district judge.
Federal judicial service On December 18, 2019, President
Donald Trump announced his intent to nominate Cullen to serve as a
United States district judge of the
United States District Court for the Western District of Virginia. The ABA Standing Committee on the Federal Judiciary rated Cullen as a "well-qualified" nominee, its highest possible rating. On February 4, 2020, his nomination was sent to the Senate. President Trump nominated Cullen to the seat vacated by Judge
Glen E. Conrad, who assumed
senior status on December 11, 2017. On March 4, 2020, a hearing on his nomination was held before the
Senate Judiciary Committee. On May 14, 2020, his nomination was reported out of committee by a 17–5 vote. On September 9, 2020, the
United States Senate invoked cloture on his nomination by a 77–18 vote. On September 10, 2020, his nomination was confirmed by a 79–19 vote. He received his judicial commission on September 15, 2020.
Notable rulings In July 2025, the chief judge of the United States Court of Appeals for the Fourth Circuit appointed Cullen to preside over
United States v. Russell, et al., the Trump administration's lawsuit against all of the active and semi-retired federal district judges in Maryland. On August 26, 2025, Cullen issued a 39-page opinion dismissing the case in favor of the judges. He concluded that the administration's suit violated the separation of powers, was prohibited by the doctrine of judicial immunity, and was not otherwise authorized by law. Cullen also cited numerous instances in which administration officials had publicly criticized federal judges, noting that "[a]lthough some tension between the coordinate branches of government is the hallmark of our constitutional system, this concerted effort by the Executive to smear and impugn individual judges who rule against it is both unprecedented and unfortunate." ==Book==