(L-R) Michael Petrella, Amanda Devereux and Sean O'Shea, partners at Cadwalader, Wickersham & Taft.

A high-profile litigation team of three Boies Schiller Flexner partners in New York has left to launch a trial practice group at Cadwalader, Wickersham & Taft.

Sean O'Shea, Michael Petrella and Amanda Devereux are expected to join Cadwalader on Friday as litigation partners, with O'Shea serving as chair of the firm's trial practice group. They will be joined by another Boies Schiller lawyer, Marc Feingold, who will be a senior attorney at Cadwalader to support the team. The group focuses on both commercial and white-collar defense litigation.

All four lawyers joined Boies Schiller nearly three years ago when the firm acquired O'Shea's boutique, O'Shea Partners. Before founding the white-collar criminal defense boutique, O'Shea served in the Eastern District of New York U.S. Attorney's Office, where he was chief of the business securities fraud section.

When he joined Boies Schiller in 2016, O'Shea said the firm presented fewer potential client conflicts than other firms because he sued “a lot of financial institutions” and Boies didn't have a traditional Wall Street banking presence.

In a Thursday interview, O'Shea said his practice has shifted and he no longer exclusively focuses on plaintiffs-side litigation matters. Lately, he has been getting engagements for both plaintiff and defense matters, he said.

“I expect there will be some conflicts at Cadwalader, including that I won't be able to sue financial institutions, but the flip side is that I will be able to represent them. I look forward to that,” O'Shea said, adding he doesn't have any cases now that are adverse to banks.

O'Shea, who worked with a recruiter in the move, said he was also attracted to Cadwalader's broader focus and its full-service capabilities, as well as the resources and support the firm could offer the team's practice. If a client comes to him for a large pressing matter, “I'm able to go down the hall” at Cadwalader, he said.

“It's just an additional step up,” he said about the move.

He said he was also attracted to the potential to chair the practice at an elite firm. “This is an opportunity you can't pass up,” O'Shea said. “When they come calling, it's pretty easy to listen.”

He said all his clients are joining him at Cadwalader, including Jay Alix, the founder of consulting firm AlixPartners, who is suing rival McKinsey & Co. in Manhattan federal court over racketeering claims to conceal conflicts of interest in bankruptcy cases. The team is also pursuing individual challenges to McKinsey's conduct in active and closed bankruptcies around the country.

Besides representing executives in investigations, he said he also represents homebuilder Lennar Corp. in defense of mortgage-backed securities claims.

Jason Halper, Cadwalader's global litigation chair, said in a statement that the three partners “are all well known and highly respected by our clients.”

O'Shea said his book of business is “substantial,” declining to provide a value, but he said he didn't think that was the reason Cadwalader was hiring him. “Cadwalader is looking at this as adding for the future—and I am too—and building out their litigation practice,” O'Shea said.

O'Shea said economic factors were not an impetus to move, and his compensation at Cadwalader is “pretty comparable” to that at Boies, noting “both firms are highly successful.”

O'Shea said he was leaving Boies Schiller on good terms, noting he has closely worked with founder David Boies over the years. Calling this a “friendly departure is an understatement,” he said.

“We wish Sean and his colleagues well in their next endeavor,” said Boies Schiller managing partner Jonathan Schiller, in a statement.

Coinciding with two years of fast growth in profits per equity partner, Cadwalader has added a series of high-profile lateral lawyers. Over about 18 months, Cadwalader said its litigation group has added six lateral partners, including Ellen Holloman, Todd Blanche, Kyle DeYoung, Jonathan Watkins, Joel Mitnick and Melis Acuner.

Outside of litigation, the firm this year added Vivian Maese, who was co-chair of Latham & Watkins' financial institutions and fintech practice groups.

The firm, just like other Am Law 100 firms, is also not immune to lateral departures. Last year, for instance, antitrust attorney Amy Ray moved to Orrick, Herrington & Sutcliffe; London litigator Steven Baker went to White & Case, and a four-partner restructuring team moved to Milbank.