Biography
David A. O’Neil is a litigation partner and member of
the firm’s White Collar & Regulatory Defense Group.
Recommended by Legal 500 us (2017), his practice
focuses on white collar criminal defense, internal
investigations, privacy and cybersecurity, congressional
investigations, and AML/sanctions enforcement
defense. Mr. O’Neil is recognized by Chambers USA
(2018) as a leading lawyer in White-Collar Crime &
Government Investigations.
Prior to joining Debevoise in January 2015, Mr. O’Neil served for eight years in
prominent positions within the Department of Justice. In early 2014, the
President and Attorney General designated Mr. O’Neil to lead the Criminal
Division, where he was responsible for supervising more than 600 attorneys
investigating and prosecuting the full range of federal crimes, including
corporate malfeasance, cybercrime, fraud offenses and money laundering. Mr.
O'Neil also served as Deputy Assistant Attorney General for the Fraud Section.
In that capacity, he supervised more than 100 prosecutors engaged in
nationwide enforcement against FCPA violations, healthcare fraud, and
securities and financial fraud.
Before moving to the Criminal Division, Mr. O’Neil served for three years as Senior Associate Deputy Attorney General and Chief of Staff to the Deputy
Attorney General, the Department's second-in-command. In that role, he was
part of DOJ’s core management team with direct supervisory responsibility for
more than two dozen attorneys. He participated in a broad range of high-profile
matters, including significant FCPA prosecutions, the LIBOR investigations,
and high-profile investigations of financial institutions for money laundering
and Bank Secrecy Act violations.
Mr. O’Neil oversaw the DOJ’s response to multiple congressional investigations
and brokered a landmark agreement with major technology companies over
disclosures of government demands for customer information. In addition, Mr.
O’Neil participated in negotiations with the Swiss government over the
framework of Swiss cooperation in what eventually became the DOJ tax
program.
In 2009, Mr. O’Neil served as Assistant to the Solicitor General. He argued three
cases in the U.S. Supreme Court, authored more than 50 briefs filed with the
Supreme Court, and handled appeals from high-profile white-collar criminal
convictions.
Mr. O’Neil began his career at DOJ as a federal prosecutor in the U.S. Attorney’s
Office for the Southern District of New York. As an Assistant U.S. Attorney, he
tried numerous cases to successful jury verdicts and argued several appeals. He
worked on multiple cases involving financial institutions, including bank fraud,
mortgage and identity-theft matters.
Mr. O’Neil's recent publications include “Staying A Step Ahead,” International
Financial Law Review (July, 2015), “Enforcement Scrutiny Falling On
Individuals,” The National Law Journal (May, 2015) and “New York State
Department Of Financial Services Expands Its Cyber Focus To Insurers,” FC&S
Legal (April, 2015).
Mr. O’Neil earned his J.D., magna cum laude, in 2000 from Harvard Law School,
where he was an Editor of the Harvard Law Review. He graduated magna cum
laude from Princeton University, with a B.A. in History in 1995.
Upon graduation from law school, he clerked for two years, first for Judge
Robert D. Sack of the U.S. Court of Appeals for the Second Circuit and then for
U.S. Supreme Court Justice Ruth Bader Ginsburg.