Bloomberg Law
Jan. 9, 2023, 6:18 PM

Paul Hastings Drops Ex-Proskauer COO Accused of Stealing Secrets

Justin Wise
Justin Wise

The former Proskauer Rose executive accused of stealing sensitive business secrets from the law firm has lost his job at rival Paul Hastings in wake of Proskauer’s lawsuit against him.

Jonathan O’Brien, who resigned as Proskauer’s chief operating officer in December, had been set to join Paul Hastings, according to a person familiar with the matter, who said the firm was not aware of any of O’Brien’s alleged activities until they were made public.

“Mr. O’Brien is not joining Paul Hastings and we do not comment on any firms’ personnel matters,” a Paul Hastings spokesman said in a statement.

New York-based Proskauer sued O’Brien in Manhattan federal court Dec. 27, claiming that he had pilfered electronic files relating to Proskauer’s financials, strategy, practice information, and billing rates before abruptly announcing his resignation days earlier. O’Brien also stole a hard copy of the its “Black Book Binder” containing info on partner compensation and allocations of firm profits, according to the lawsuit.

A judge granted the firm’s request for a temporary restraining order, requiring O’Brien to return any proprietary files he took from the firm by Jan. 6. O’Brien, through an attorney, has denied the allegations of stealing trade secrets and other sensitive business records.

O’Brien returned from an international vacation on Jan. 5 and “promptly returned” work devices and “materials he brought with him overseas in order to conduct Proskauer business,” his lawyer, Russell Beck said via email. O’Brien was set to officially leave Proskauer Jan. 6, according the lawsuit.

“While it is unfortunate that an apparent overreaction based on Proskauer’s mistaken assumptions has improperly interfered with Mr. O’Brien’s planned position at Paul Hastings, he nevertheless looks forward to resolving this entire matter quickly and continuing his successful career in the legal field,” Beck said.

Proskauer’s lawsuit, while not mentioning Paul Hastings by name, claimed that O’Brien had told a colleague that the firm’s management would be “very angry” when they found out his new employer. The firm claimed that the proprietary records he stole would be “highly useful” to competitors and come at a huge expense.

Proskauer and Paul Hastings are among the 50 largest law firms in the US, each employing hundreds of attorneys and gross revenue surpassing $1 billion in 2021, according to the American Lawyer.

O’Brien, who is a UK citizen and not a lawyer, joined Proskauer in 2015 and served as its chief operating officer over the last five years. His career has included previous stints as the global finance director of The Boston Consulting Group and chief financial officer of Fidelity Worldwide Investment, according to his LinkedIn profile.

A Paul Hastings spokesman declined to comment on questions relating to the firm’s hiring of O’Brien.

The case is Proskauer Rose LLP v. O’Brien, S.D.N.Y., No. 1:22-cv-10918 (1/4/2023).

To contact the reporter on this story: Justin Wise at

To contact the editors responsible for this story: Chris Opfer at; John Hughes at

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