Reacting on The Colbert Report to the new congressional Republican majority’s vows to investigate the Obama administration, Abbe Lowell joked that he’d printed a lot of extra business cards — some blue, some red.

Lowell, who heads his firm’s white-collar criminal defense group in Washington, has represented dozens of members of Congress, lobbyists and government officials. A litigator for more than 20 years, Lowell is the go-to lawyer when it comes to constitutional issues stemming from leak investigations and prosecutions.

In 2009, after four years of litigation, federal prosecutors dismissed charges against two of Lowell’s clients, lobbyists for the American Israel Public Affairs Committee accused of providing classified information to journalists.

“A meaningful debate about the Espionage Act and changes to the law are long overdue,” Lowell testified in December on Capitol Hill.