Dickstein Shapiro has lost a chunk of its antitrust practice, with five Washington lawyers departing to open an office for the small national litigation firm Zelle LLP.

James Robertson Martin will co-chair Zelle's antitrust and unfair-competition practice after serving as the partner in charge of business development for the group at Dickstein Shapiro, Zelle announced Tuesday. Another partner moves with him — Jennifer Duncan Hackett, who made partner at Dickstein Shapiro in 2013 after negotiating a $500 million antitrust settlement for clients ZF Meritor and Meritor Inc., according to The Washington Post. Their group also includes two associates and a senior counsel — Nick Cheolas, Allison Vissichelli and Woody Peterson, respectively.

The firm statement said Martin worked on litigation related to the London InterBank Offered Rate, an area of business Dickstein Shapiro leaders had touted in recent years. The group represents Freddie Mac and the Federal Deposit Insurance Corp.

This move, Martin said, frees the group from conflicts that could arise at a larger law firm that represents major banks.

The antitrust group had worked alongside Zelle attorneys on corporate plaintiffs-side cases since Martin, 52, joined Dickstein Shapiro as a mid-level associate in 1999, he said in an interview Tuesday.

He started at Dickstein Shapiro to work on the price-fixing litigation against the vitamin industry, a pinnacle in the Washington-based firm's history that led to a $2 billion settlement for the firm's clients and a windfall, because of a contingency, for the firm's own finances. Hackett, 41, also worked on the vitamin case earlier in her career.

“When we decided to make this move, there are a handful of firms we could take our practice to. We really like the people,” she said Tuesday. “The motivation here was really not to do something completely different than we're already doing.”

The departures hasten the bleed of Dickstein Shapiro partners jumping to other law firms. Since the beginning of the year, Dickstein Shapiro has lost four partners as laterals to other firms. The 2015 Am Law 200 firm now has fewer than 140 lawyers.

Zelle has about 75 lawyers in eight offices around the country and in London.

“This group significantly expands the depth and breadth of our antitrust practice,” Kerry Brown, a member of Zelle's executive committee, said in a statement. “They bring great legal skills and experience on some of the largest antitrust cases in the country.”

Martin said he doesn't plan on taking the new office on a recruitment spree. “I see us more of an East Coast practice. This allows us to catch all the time zones,” he said.

When asked about the timing of his group's move, he said, “It was time.”

Spokespeople at Dickstein Shapiro did not immediately respond to a request for comment, and D.C.-office managing partner Richard Leveridge, the head of the firm's antitrust and financial-services practice who acts as co-counsel for some of Martin and Hackett's clients, was unavailable.

This story was updated with additional information about the moves.