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Paul Hastings LLP

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William Sullivan

Work (213) 683-6252
Paul Hastings LLP

Work Department

Litigation/Securities Litigaiton


William Sullivan is the Chair of the Los Angeles Litigation Department. Mr. Sullivan has substantial experience in complex business litigation, including the representation of public companies in the defense of federal and state securities class actions, derivative actions and regulatory proceedings. Most of these cases involve claims arising out of public offerings, mergers and acquisitions, disclosure obligations, insider trading, accounting practices or allegations of breaches of fiduciary duties. Mr. Sullivan argued and won the ground-breaking Dura Pharmaceuticals case before the United States Supreme Court which established the standard for loss causation in federal securities class actions. Mr. Sullivan is a veteran trial lawyer who has tried cases involving stock valuations, fraud, forgery, license agreements, internet contract issues, whistle blower claims, employee termination, lender liability, fiduciary duties and breach of real estate contracts, among others. Mr. Sullivan has significant experience counseling public companies and frequently counsels boards of directors in special investigations. Mr. Sullivan also represents clients before the Securities and Exchange Commission. Mr. Sullivan has substantial appellate experience, including before the United States Supreme Court. Previously, Mr. Sullivan served as the Global Chair of the Paul Hastings Litigation Department and Chair of the firm's Securities Litigation practice.


LEGAL BACKGROUND: PAUL, HASTINGS, JANOFSKY & WALKER, LLP Global Chair of the Litigation Department Partner, 2003 to 2013; Member, Litigation Steering Committee Global Chair, Securities Litigation and Enforcement Practice Group BROBECK, PHLEGER & HARRISON, 1981 to 2003; Partner, 1984; firm-wide Managing Partner, 1996 to 1998; firm-wide Securities Litigation Practice Group Leader, 2002 to 2003; Managing Partner, San Diego office, 1992 to 1996 and 2001 to 2002; Member, firm Policy Committee, 1996 to 2000; Member, Executive Committee, 1991 to 1994; Chair, Litigation Group, San Diego, 1989 to 1996 CHICKERING & GREGORY, Associate, 1977 to 1981, San Francisco, California and Washington, D.C. offices ADMITTED TO PRACTICE IN: State of California United States Supreme Court United States Court of Appeals for the Third, Ninth and Tenth Circuits District of Columbia Circuit and Federal Circuit United States District Court for the Northern, Eastern, Southern and Central Districts of California


American Bar Association: Member, Litigation Section State Bar of California: Member, Litigation Section Chair, Federal Practice Committee, 1992 Co-chair, Litigation Section Statewide Committee for Law and Motion and Discovery, 1991-92 Chancery Club, Los Angeles, CA San Diego County Bar Association: Member, Litigation Section J. Clifford Wallace Inn of the Court, Founding Master, San Diego Association of Business Trial Lawyers: Founding Member Board of Governors, San Diego California Young Lawyers Association: Board of Directors, 1986-1989 Secretary 1987-1988 First Vice President 1988-1989 American Bar Association: Young Lawyers Division Assembly, Member, 1985 and 1986 American Bar Association: Young Lawyers Division Host Committee for 1987 ABA Convention, Member Bar Association of San Francisco: Board of Directors, 1985 ex officio State Court Committee on Rules and Procedures in Civil Cases: Member, 1984 Executive Committee to the State Bar Conference of Delegates: Member, 1984-85 Community Law Week: Chairman, 1984 Barristers Club of San Francisco: President, 1985 Vice President, 1985 Director, 1984-1986 Co-Chair, Litigation Committee, 1983 and 1984 American Arbitration Association: Member, Special Panel for Large and Complex Cases Board of Trustees, The Bishop’s School: Chair, Strategic Planning Committee 2000-2003 Board of Trustees, La Jolla Country Day School: President 1993-1996 U.S. Supreme Court Historical Society UCLA Law Alumni Association Mr. Sullivan was honored as California Lawyer of the Year in Securities Law and was recognized as one of the Top 30 Securities Litigators in California and one of the Top 100 Most Influential Lawyers in California. The Los Angeles Business Journal named him one of the Top 100 Lawyers in Los Angeles. He was honored by his peers as one of The San Diego Daily Transcript’s Top 10 San Diego Attorneys of 2006. He is listed in Best Lawyers in America. He has been recognized as a leader in his field by Chambers. He is listed as a Legal Superstar in Securities Law 360.


Mr. Sullivan graduated with distinction at the University of California at Berkerley, where he received his A.B. in 1974. He attended the University of California at Los Angeles School of Law and received his J.D. in 1977.

United States: Dispute resolution


Within: Appellate

Paul Hastings LLP’s appellate practice is jointly chaired by San Francisco-based Paul Cane and Washington DC-based Stephen Kinnaird. Assisted by associate Sarah Besnoff, Kinnaird appeared on behalf of Jacobs Engineering in Jacobs Engineering Group Inc. v ConAgra Foods, Inc. before the Nebraska Supreme Court, which affirmed the district court’s judgment awarding Jacobs Engineering $108.9m of settlement payments for wrongful deaths resulting from ConAgra’s negligent plant explosion. In a shareholder suit at the Ninth Circuit, Los Angeles-based William Sullivan convinced the panel to unanimously affirm a prior judgment entered in favor of William Weidner, the former President of casino operator Las Vegas Sands. John Phillips (San Francisco) and Yar Chaikovsky (Palo Alto) are also noted.

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Financial services litigation

Within: Financial services litigation

With strong capabilities on both coasts, as well as key centers including Houston and Chicago, the 'superb' team at Paul Hastings LLP is able to effectively represent a broad range of financial services entities on private litigation and agency investigations across the country. In addition to his stellar securities litigation reputation, New York-based partner Barry Sher also regularly defends banks in other disputes, which includes his work alongside Anthony Antonelli for Barclays as a defendant in the high-profile supranational, sovereign and agency bond antitrust litigation. Los Angeles-based partner William Sullivan is also recommended. Other clients include Goldman Sachs, Royal Bank of Canada and Morgan Stanley. Douglas Flaum joined Goodwin in March 2019.

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M&A litigation: defense

Within: M&A litigation: defense

Paul Hastings LLP has significant litigation capability on both coasts, as well as in other key centres such as Houston and Chicago. It frequently acts for leading financial institutions in deal-related litigation and recently handled two key cases for Goldman Sachs. The first saw the firm handle a $50m claim in the New York State Supreme Court arising from GS Group’s investment in financial services research provider Netologic, Inc. The second case saw fellow co-chair Peter Stone in Palo Alto represent the client in its role as financial adviser to Amazon, Inc in matters arising from its $13.7bn acquisition of Whole Foods Market. Veteran litigator William Sullivan in Los Angeles handled a $500m case for Vance Street Capital as seller in a post-acquisition dispute with Precision Castparts Corporation. Samuel Cooper in Houston is also recommended. Douglas Flaum joined Goodwin.

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