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T: +1 212.351.3808
F: +1 212.351.5272

New York Office
200 Park Avenue
New York, NY 10166-0193, USA


Adam H. Offenhartz is a partner in the New York office of Gibson, Dunn & Crutcher. He is a member of Gibson Dunn's Securities Litigation, Mergers & Acquisitions and International Arbitration Practice Groups. Mr. Offenhartz focuses on corporate control contests, activist investor related litigation as well as shareholder plaintiff class strike suits. In this and other contexts, Mr. Offenhartz regularly seeks injunctive relief or opposes such applications and handles related appeals. He has tried jury and non-jury cases involving mergers and acquisition battles, related shareholder class and derivative actions, appraisal actions, shareholder proposals, board disputes, restrictive covenants and earn-out disputes among other matters.

Mr. Offenhartz also has an active domestic and international arbitration practice with an emphasis on insurance and reinsurance disputes and cross-border issues. He has also handled a number of regulatory, disciplinary and ad hoc proceedings. Mr. Offenhartz regularly represents plaintiffs/claimants for whom he has recovered substantial sums or achieved significant injunctive relief.

Mr. Offenhartz was named a 2011 MVP in securities litigation by Law 360 for his work in corporate control and shareholder class strike suit litigation, and has been recognized repeatedly as a leading litigator in Benchmark Litigation: The Definitive Guide to America's Leading Litigation Firms and Attorneys.

Mr. Offenhartz joined Gibson Dunn in 1989 after earning his Juris Doctor from the University of Chicago Law School. He is a graduate of Harvard College, where he received a degree in American History and Literature.

Representative Corporate Control Matters

  • Marriott International: Lead litigator representing Marriott Hotels in strike suit litigation seeking to prevent the combination of Marriott and Starwood Hotels. Won a rare early dismissal for Marriott on aiding and abetting claims in Maryland State Court.
  • Transatlantic Re: Lead litigator representing Transatlantic and its directors in litigation brought by hostile bidder and shareholder plaintiffs alleging breaches of fiduciary duties in connection with the potential merger or sale of Transatlantic. Won key victories before Delaware Chancery Court in which the Court refused to grant plaintiffs' motions to expedite proceedings and to set a preliminary injunction hearing date. Also filed an action in Delaware Chancery Court that forced hostile bidder to withdraw invalid proxy materials that conflicted with company bylaws. These victories stopped the lawsuits in their tracks and paved the way for a successful negotiated transaction between Transatlantic and another bidder. Also brought an action in federal court under the securities laws against the hostile bidder.
  • Outside director of ChinaCast:  Lead litigator representing an outside director of ChinaCast in obtaining a rarely granted TRO from the Delaware Chancery Court postponing an annual meeting so that our client could run a competing slate of directors.  With the TRO in place and the meeting date moved, our client's director nominees were elected to the ChinaCast Board of Directors by a wide margin.
  • Tenet Healthcare: Lead litigator representing Tenet in successful defense of unsolicited takeover offer from Community Health Systems. Less than one month after Tenet filed a complaint against Community alleging misstatements in Community's proxy solicitations, Community withdrew its takeover proposal. Also defeated efforts by plaintiff shareholders to obtain expedited discovery and to schedule a preliminary injunction regarding breach of fiduciary duty allegations in Nevada state court. The court subsequently granted Tenet's motion to dismiss the shareholder complaint in its entirety before any discovery.
  • iBasis Inc.: Lead litigator for iBasis in connection with an all-cash, all-shares tender offer made by its majority shareholder Koninldijke KPN N.V. ("KPN") for all of the outstanding shares of iBasis. Gibson Dunn litigated the case through trial, but before the Delaware Chancery Court issued a ruling, the case settled after KPN agreed to increase its tender offer price to $3.00 per share. The offer price represented a 130.8% premium for shareholders over the closing price of iBasis shares on the last trading day prior to the announcement of KPN's tender offer, and nearly a 100% increase from KPN's initial offer price of $1.55 per share.
  • Delcath Systems: Lead litigator on behalf of Delcath in successful defense of consent solicitation by an activist shareholder to replace the entire board. Despite receiving sufficient shareholder votes, the activist investor was prevented from replacing the board with his nominees because of the various restraining orders and the preliminary injunction we won in the U.S. District Court for the Southern District of New York.
  • Parlux Fragrance: Lead litigator on behalf of Parlux Fragrance in successful defense of consent solicitation by an activist shareholder to replace the entire board. After achieving, in effect, a stay on the consent solicitation following our emergency application for relief on both antitrust and securities grounds in the U.S. District Court for the Southern District of New York, and following pitched discovery, Parlux resolved the battle without giving control to the insurgents.
  • Atlantic Coast Airlines: Lead securities litigator on behalf of Atlantic Coast Airlines in successfully preventing an unsolicited takeover by Mesa Airlines. We initiated litigation in the D.C. District Court seeking to enjoin the consent solicitation and tender offer. Mesa brought claims against Atlantic Coast in Delaware Chancery Court. Following extended document and deposition discovery, we amended our federal complaint to include antitrust claims. Following even further expedited discovery and a multiday evidentiary hearing, the Court enjoined Mesa's bid.
  • Maxwell Shoe: Lead litigator on behalf of Maxwell Shoe in defending against a consent solicitation and tender offer from Jones Apparel. We initiated a securities action in federal court in Boston. Jones brought claims against Maxwell Shoe in the Delaware Chancery Court. Following discovery, we were able to negotiate a greatly improved offer for Maxwell Shoe.
  • ArvinMeritor:  Lead litigator on behalf of ArvinMeritor for its unsolicited bid for Dana.  We filed actions against Dana in federal court in the Western District of Virginia and in state court in Buena Vista, Virginia.  We also defended an action brought by Dana in state court in Ohio.  Due to changing market conditions, ArvinMeritor decided not to proceed with its bid.

Mr. Offenhartz regularly represents parties in public deals challenged by the shareholder strike suit bar. He has defeated motions to enjoin such deals, won dismissals of such claims and achieved beneficial settlements of other such challenges. Mr. Offenhartz regularly advises companies, special board committees and shareholders on corporate control, mergers and acquisitions and litigation-related matters.

Representative Arbitration Matters

  • Leading international insurance organization:  Lead litigator representing a leading international insurance organization in obtaining a preliminary injunction in aid of arbitration in the Delaware Chancery Court preventing former business partner of the insurer from using the insurer’s trade secrets and confidential information.  Key victory paved the way for a successful resolution for client during arbitration proceedings.
  • General Growth Properties, Inc.:Co-lead litigator on behalf of General Growth Properties (GGP) in a multiday arbitration against the heirs to the Howard Hughes estate with respect to development rights and an earn-out provision.After the liability phase of the hearing, the arbitration panel ruled in favor of GGP on six of seven of the heirs’ claims, and, with respect to the seventh claim, found a technical breach awarding $1 in damages.
  • Texaco (now Chevron):  Lead litigator on behalf of Texaco (now Chevron) in an international arbitration before a United Nations arbitration panel that sat in Geneva, London and Washington, D.C. which resulted in a $550 million award arising from damage to oil facilities during the first Gulf War.  Chevron obtained the largest award granted to any U.S. corporate claimant.  The award has been fully satisfied.
  • Leading international insurance organization:  Lead litigator in a reinsurance arbitration on behalf of a leading international insurance organization arising out of an auto warranty program that resulted in a $90 million recovery for the client.
  • Leading international insurance organization:  Represented a leading international insurance organization in a series of reinsurance arbitrations with an Australian reinsurer resulting in a more than $18 million recovery for the client.

Mr. Offenhartz has handled UNCITRAL arbitrations in Brazil and New York; ICC arbitrations in Toronto, Paris and Vienna; and has supervised litigation and investigations in Argentina, Brazil, Ecuador and Thailand.

Additional Representative Matters

  • Vista Outdoors:Lead litigator representing Vista Outdoors in high-stakes earn-out dispute initiated by Vista against the sellers of a business Vista acquired.Following expedited discovery, won summary in the SDNY on affirmative claims and dismissal of defendants' counterclaims.The Court's memorandum and order is now the leading opinion addressing the duty of good faith and fair dealing under NY law.
  • Leading international insurance organization:Lead litigator defending client against billion dollar claim for misappropriation of trade secrets and breach of confidentiality in the SDNY.Following extensive discovery, motion practice and numerous court hearings and shortly after the close of fact discovery, plaintiffs gave up and dismissed the action with prejudice.
  • Staffing company:  Lead litigator representing plaintiff staffing company in successful effort to enjoin four former employees and a competitor from working together in violation of certain non-compete and related provisions.  Handled the case through four hearings before the trial court and an emergency appeal to the Second Circuit.  Case settled with defendants agreeing to broad injunctive relief and making a significant payment to plaintiff.  Handled a similar matter for a large professional services firm with similar success in winning injunctive relief.
  • Confidential client:  Lead litigator during a three-week jury trial on copyright infringement and Lanham Act claims.  Case resolved favorably for the client immediately before jury deliberations.
  • European banks:  Represented four plaintiff European banks in a bank fraud and conversion case in the Southern District of New York related to oil trade finance that has resulted in over $70 million in recovery.
  • Senior banker:  Represented a senior banker in an NASD disciplinary proceeding.  Matter resolved on the eve of the evidentiary hearing on very favorable terms.




  • University of Chicago - 1989 - Juris Doctor
  • Harvard University - 1985 - Bachelor of Arts


  • New York Bar

Recent Publications

January 28, 2010