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Sean F. O'Shea

New York

t: 212 303 3311
f: 212 446 2350
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Areas of Practice



Global Investigations and White Collar Defense

Securities Litigation


Northwestern University School of Law, J.D., 1981; Notes and Comments Editor of the Northwestern University Law Review; Recipient of the Adlai Stevenson Award for writing best appellate brief in the Julius Miner Moot Court Competition

University of Illinois, B.A., 1978


New York


United States Supreme Court

United States Court of Appeals: Second, Sixth, and Seventh Circuits

United States District Court: Southern and Eastern Districts of New York, Western District of Michigan and Northern District of Illinois

United States Tax Court

Sean O'Shea, the former Chief of the Business/Securities Fraud section of the United States Attorney's Office for the Eastern District of New York, is a highly experienced, aggressive trial lawyer, and ranks among the most skilled cross-examiners in the legal profession.  His practice focuses on complex business and white collar litigation.  Mr. O’Shea has represented clients ranging from large corporations, to prominent private equity and hedge funds, to senior executives at major corporations.  He has tried more than 85 cases to verdict, including federal and state jury and bench trials, arbitrations, and administrative proceedings.  A Fortune magazine profile of one his many notable cases described him as “a top draw ... one of the toughest, most resourceful [of lawyers] ..." Mr. O’Shea was profiled in Lawdragon as one of the 500 top lawyers in the United States. Condé Nast Portfolio has ranked Mr. O'Shea as one of the top ten White Collar criminal defense lawyers in New York City, noting his particular skill at avoiding indictment for his clients.

During his decade-long tenure as a federal prosecutor, Mr. O'Shea tried more than thirty-five jury trials to verdict and appeared as lead appellate counsel for the Department of Justice in dozens of appeals to the United States Court of Appeals for the Second Circuit.  Among many other prominent cases receiving local and national media attention, Mr. O'Shea led the fraud prosecution of New York lawyer Harvey Myerson, then one of the nation’s leading trial lawyers. The trial received extensive media attention in Time magazine and other outlets.  The New York Law Journal described Mr. O'Shea as having delivered a "polished 50-minute opening [statement] spelling out in simple, but starkly memorable terms the government's case" and recounted how the opening statement "skillfully unfolded the story" of how Myerson turned a Park Avenue law firm into a RICO enterprise. Mr. Myerson was convicted on multiple counts of fraud after a five week trial.

Mr. O’Shea has received numerous awards and commendations from the Department of Justice, the Federal Bureau of Investigation, and other law enforcement agencies for his work in significant white collar crime matters.  He has been a featured speaker on many occasions before federal law enforcement groups including the Federal Bureau of Investigation and United States Postal Inspection Service. He has also served as an instructor in trial tactics and courtroom procedures classes at the Federal Bureau of Investigation Academy at Quantico, Virginia.  Upon his departure from the United States Attorney's Office to return to private practice, F.B.I. Director Louis Freeh wrote that Mr. O'Shea's "efforts as a prosecutor, as well as an investigator, were keys to the success of our White Collar Crime Program." He was also commended by Assistant Director of the F.B.I. James Kallstrom for his work in a case against United States Aviation Underwriters. Mr. Kallstrom described Mr. O'Shea as being the "architect of the investigation and the prosecution presenting unique legal issues and facts [flowing out of the Pan Am 103 Lockerbie bombing investigation]." 

Before joining Boies Schiller & Flexner, LLP, Mr. O’Shea practiced at O’Shea Partners LLP, a litigation boutique specializing in complex business litigation and white collar criminal litigation.  At O’Shea Partners, Mr. O’Shea remained exceedingly trial-active, conducting approximately 50 federal and state jury and bench trials, arbitrations, and administrative proceedings. Major corporations and high-profile business executives routinely seek his counsel, particularly for his skill in the courtroom.  For example, Mr. O'Shea was retained as trial counsel to Visa U.S.A., Inc. in the In re Visa Check/MasterMoney Antitrust case in the United States District Court for the Eastern District of New York. The plaintiffs sought over $100 billion in damages and challenged Visa's requirement of universal acceptance of its credit and debit cards as an illegal tying arrangement.

Some of his other representative civil and criminal matters include:

  • Won a judgment exceeding $100 million for a private equity firm in a 10b-5 securities fraud and breach of contract litigation against Cendant Corporation in parallel actions in state and federal court flowing out of Cendant's criminal accounting fraud.
  • In NML Capital, Ltd. v. Republic of Argentina, No. 12-105-cv(L), Mr. O’Shea was engaged on an emergency basis, and helped assemble a  consortium of financial firms (including Brevan Howard, AllianceBernstein, and  MFS BlackRock) holding over $1 billion in exchange bonds issued by the Republic of Argentina. Acting under severe time constraints, he won a stay from the United States Court of Appeals for the Second Circuit preventing the enforcement of an injunction entered by a federal district court that would have interfered with the Republic's payments on over $24 billion in exchange bonds. The stay enabled the Republic's exchange bondholders to receive $3 billion in payments.
  • Mr. O’Shea persuaded the Antitrust Division of the United States Department of Justice ("DOJ") not to indict a senior executive at a multinational corporation, who had been identified as a target of the investigation of the optical disk drive industry.
  • Represented the founder and former president of AIG Global Real Estate in a successful action against AIG for in excess of $250 million in carried interest on all AIG real estate investments around the world. 
  • Represented the co-founder of a large internet gaming company targeted for prosecution for violation of various state and federal gaming statutes and money laundering.  Several years into the investigation, after replacing prior counsel who had recommended a guilty plea, Mr. O’Shea designed and implemented a defense strategy that resulted in the government ultimately declining to indict Mr. O’Shea’s client.  The client’s co-founder, represented by other counsel, pled guilty and agreed to pay a $300 million criminal forfeiture.
  • Prevailed at trial in seeking return of funds seized by the IRS, which claimed the client company had structured its bank deposits to evade taxes. After waiving jury trial, Mr. O’Shea employed a technical tax defense, aggressively cross-examining government witnesses and agents. After trial, the court ordered the forfeited funds returned and the client’s legal fees reimbursed.
  • Obtained a multi-million dollar award for an executive who conceived and introduced the Refco/Thomas H. Lee leveraged buyout. The trial was conducted almost entirely by cross-examination of adverse witnesses who denied the involvement of Mr. O'Shea's client.
  • Represented a prominent private equity firm as the plaintiff in a securities fraud case venued in the United States District Court for the Southern District of New York. After the original complaint was dismissed, Mr. O’Shea replaced the client’s existing counsel, formulated new causes of action, and filed an amended action.  The revamped complaint survived the defendants' motions to dismiss, and Mr. O’Shea thereafter engineered a favorable eight-figure settlement prior to any deposition discovery.
  • Successfully represented an insurance industry executive threatened with indictment in a high profile investigation conducted by the New York Attorney General.  Mr. O’Shea replaced prior counsel and persuaded the AG’s office not to indict. 

Selected Professional Awards and Associations

Lawdragon’s 500 Leading Lawyers in America

Regularly listed among Top Lawyers by New York Super Lawyers Magazine

National Association of Criminal Defense Lawyers

Ranked Top Ten White Collar Criminal Defense Lawyers in New York City, Condé Nast (2007)

Related News

Fifty-three Attorneys Recognized as New York Metro Super Lawyers (October 10, 2016)

AIG settles $275M lawsuit on eve of trial (Reuters)

Sean O'Shea featured in Lawdragon Magazine (Lawdragon)

Sean O'Shea Debates Argentina Bondholder Issues at EMTA (New York)

Sean O’Shea obtains Second Circuit order allowing $3BN escrow payment to bondholders (Financial Times)

Ruling That May Have Triggered Argentina Default Is Stayed (The Wall Street Journal)

Argentina Wins Delay of Order Forcing Bond Payment (Bloomberg)

Sean O’Shea cited by prominent lawyer as his most feared adversary (Law360)

Sean O’Shea wins appeal of $100M judgment for private equity client (Law360)

Sean O’Shea obtains finder fee arbitration judgment in REFCO deal (Business Insider)

Sean O’Shea client cleared in AIG criminal investigation (The New York Times)

Sean O’Shea trial win featured in book by NYT reporter (2003)

Sean O'Shea Profiled in La Nacion (La Nacion)

Sean O’Shea client cleared in WTC investigation (The New York Times Magazine)

Government Service

Chief of the Business and Securities Fraud Unit, United States Attorney’s Office for the Eastern District of New York (1990-1996)

Assistant United States Attorney, Criminal Division, United States Attorney’s Office for the Eastern District of New York (1986-1990)