Investigations practices have remained lucrative for Washington, D.C., law firms in the first half of the year, with government agencies ramping up enforcement across multiple industries and both chambers of Congress pursuing aggressive oversight agendas.

"The pace of congressional oversight has been unrelenting and you see that across chambers, both in the Senate and the House," said Joel Green, co-chair of Wilmer Cutler Pickering Hale and Dorr's congressional investigations practice. "You see it across committees—that typical oversight committees are very, very active, but then there are also new select committees and a number of committees that typically don't do a tremendous amount of oversight or hearings."