William A. Maher, Partner

Litigation & Dispute Resolution Group


William Maher is a founding member of the Firm, and leads the Firm’s Litigation & Dispute Resolution Group. In his more than 30 years of practice, Bill has had broad experience in litigating, arbitrating or mediating high-stakes commercial disputes, has tried numerous cases and arbitrations, and has argued appeals in both state and federal court. For the last 17 years, Bill has been recognized by Chambers USA (an independent evaluator of lawyers and law firms) as a leading lawyer for business disputes in New York. In 2024, Chambers USA quoted Bill’s clients as saying, "He is aggressive and fearless," and “[a]n exceptional litigator.” Chambers USA noted that Bill “is routinely engaged by financial institutions to handle diverse disputes in the MBS [mortgage-backed securities] arena, and also offers a broader commercial practice including experience in antitrust and M&A disputes.” Bill has been repeatedly recognized as a "SuperLawyer" in business litigation in New York.


  • Represents certain subsidiaries of EssilorLuxottica SA (“Essilor”), which were victims of international cybercriminals, who stole more than $270 million through 243 fraudulent payment orders from an account held at a major money center bank in New York. These subsidiaries asserted claims against the Bank for their net loss in the United States District Court for the Southern District of New York, including a refund under Article 4-A of the New York Uniform Commercial Code (“N.Y. U.C.C.”). In an Opinion & Order dated January 4, 2023, the Court denied the Bank’s motion to dismiss the Thai subsidiary’s claims under Article 4-A of the N.Y. U.C.C. The Court held that the Thai subsidiary had sufficiently alleged that the fraudulent transfers were “unauthorized” within the meaning of that statute. Essilor International SAS, et ano. v. J.P. Morgan Chase Bank, N.A., 2023 U.S. Dist. LEXIS 1327 (S.D.N.Y. Jan. 4, 2023). The case is now in the discovery phase.

  • Represented the directors of an insurance company in a purported class action lawsuit against them arising out of the insurance company’s demutualization and its simultaneous acquisition for approximately $2.5 billion by a member of the Berkshire Hathaway Group of Insurance Companies. The Trial Court agreed with Bill’s argument that the Complaint was an improper collateral attack upon the approval of the demutualization by the Superintendent of the New York State Department of Financial Services. On February 9, 2022, the New York Appellate Division, Second Department, also agreed with Bill’s argument, and affirmed the dismissal of the purported class action lawsuit on the basis of the Collateral Attack Doctrine. Castagna, et al. v. Capotorto, et al., 202 A.D.3d 748 (2d Dep’t 2022). On June 16, 2022, the New York Court of Appeals denied Plaintiffs’ motion for leave to appeal. These decisions constitute a complete victory for Bill’s clients.
  • Represents a class of entities adversely affected by an alleged conspiracy by certain financial entities to inflate the interest rates for Variable Rate Demand Obligations (“VRDOs”), bonds issued by public entities to raise funds for infrastructure and public services. The City of Philadelphia, et al. v. Bank of America Corp., et al., Case No. 19-cv-1608 (JMF) (S.D.N.Y.). On September 21, 2023, the SDNY court granted Plaintiffs' motion for class certification, officially appointed the Firm as co-class counsel, and denied Defendants' motion to exclude Plaintiffs' expert witnesses.
  • Represents holders of more than $200 million in Trust Preferred Securities (“TruPS”) against certain Defendants who allegedly facilitated and/or participated in wrongdoing that greatly diminished the value of Plaintiffs’ TruPS. In October 2022, the New York Appellate Division, First Department, largely affirmed two decisions in the Trial Court that had largely denied Defendants’ motion to dismiss the amended complaint. Alesco Preferred Funding VIII, Ltd., et al. v. ACP Re, Ltd., et al., 209 A.D.3d 558 (1st Dep’t 2022).
  • Represents interest rate swaps (“IRS”) trading platforms against certain of the largest IRS dealers alleging that the IRS dealers conspired to boycott this IRS trading platform in an effort to undermine competition in the IRS market. In re Interest Rate Swaps Antitrust Litigation, No. 16-md-2704 (JPO) (S.D.N.Y.)
  • Represented an AIG-affiliated insurance company in an arbitration against an insured concerning indemnification for payments in connection with a long-running insurance coverage dispute relating to asbestos claims from insurance policies issued in the 1980s. Following the insurer’s arbitration demand, the insured twice filed emergency applications seeking to enjoin the arbitration, and Bill successfully opposed both applications resulting in two separate courts denying the insured’s emergency applications in their entirety. The J.R. Clarkson Co. LLC v. National Union Fire Ins. Co. of Pittsburgh, Pa., 23-cv-10252-ER (Dec. 11, 2023); Cosby Valve, LLC et al. v. OneBeacon America Ins. Co., et al., 1284-cv-02705-BLS2 (Mass. Sup. Ct. Sept. 22, 2023).
  • Represented Lehman Brothers Holdings Inc., and certain of its affiliated entities (collectively, “Lehman”) for more than 12 years on numerous, significant bankruptcy and litigation matters, including the following: (i) litigations asserting indemnification claims against hundreds of mortgage loan sellers relating to Lehman’s multi-billion dollar settlements of claims litigation with Fannie Mae, Freddie Mac and trustees for hundreds of RMBS trusts, In re Lehman Brothers Holdings Inc., et al., Case No. 08-13555 (Bankr. S.D.N.Y.), Adversary Proceeding No. 16-01019 (SCC); (ii) litigation relating to Archstone, the largest real estate holding of Lehman, which was purchased by Lehman and other financial entities for approximately $22 billion, In re Lehman Brothers Holdings Inc., et al., Case No. 08-13555 (Bankr. S.D.N.Y.), Adversary Proceeding No. 11-02928 (JMP); and (iii) litigation against an affiliate of a major investment bank for breach of an approximately $1.3 billion contract related to an office building portfolio. In re Lehman Brothers Holdings Inc., et al., Case No. 08-13555 (Bankr. S.D.N.Y.), Adversary Proceeding No. 11-02764 (JMP).
  • Represented Assured Guaranty (UK) Ltd., as financial guarantor of hundreds of millions in bonds, in a lawsuit against an affiliate of a major money center bank in New York, for investing and then maintaining the underlying portfolios in subprime and Alt-A mortgage-backed securities, thereby causing very significant losses. In March 2017, after two weeks of trial, the case settled on confidential terms. Previously in the case, Bill obtained a unanimous landmark ruling from New York’s highest court that New York’s “blue sky” law, known as the Martin Act, does not preempt common-law tort claims for negligence and breach of fiduciary duty in the securities field. Assured Guaranty (UK) Ltd. V. J.P. Morgan Investment Management Inc., 18 N.Y.3d 341 (2011).
  • Represented Berkshire Hathaway Specialty Insurance Company (“BHSI”) in a lawsuit against QBE Insurance Company (d/b/a QBE North America) and certain of BHSI’s former insurance brokers and employees, who resigned from BHSI in a coordinated fashion in April 2022 and commenced work almost immediately with QBE. On May 5, 2022, Bill obtained a temporary restraining order against Defendants in the Commercial Division of the Supreme Court of the State of New York. Index No. 652049/2022. Thereafter, the case settled on confidential terms.
  • Represents MLMIC Insurance Company (“MLMIC”), one of the largest New York medical malpractice insurers, and a member of the Berkshire Hathaway Group of Insurance Companies. In 2018, MLMIC went through a demutualization process, and became a stock company, and its stock was simultaneously purchased by a subsidiary of Berkshire Hathaway in a pre-arranged sale for approximately $2.5 billion. Thereafter, certain former policyholders of MLMIC sued it for breach of fiduciary duty and misrepresentation, contending that had MLMIC advised them of a purported secret “plan” to sell itself to Berkshire Hathaway, those former policyholders would not have left MLMIC, and would have received more of the demutualization proceed payments made to MLMIC’s former policyholders. On the eve of trial, the New York Appellate Division, Second Department, agreed with Bill’s argument that, even if everything Plaintiffs alleged were true, Plaintiffs have no legitimate claim against MLMIC as a matter of law. Neurological Surgery, P.C., et al. v. MLMIC Insurance Company, 208 A.D.3d 1238 (2d Dep’t 2022). This appellate decision represents a complete vindication for Bill’s client.


Bill received his J.D. Degree from The University of Virginia School of Law, where he graduated at the top of his class as Order of the Coif and was the Managing Editor of the Virginia Law Review. He received his B.A. degree in Economics from The College of William & Mary.

Other Activities

  • Member, Board of Trustees, Ranney School (Grades K-12, Tinton Falls, NJ) (2014-2019)

  • Member, New York State Appellate Division, First Department, Department Disciplinary Committee (2009-2014)
  • Member, Council on Judicial Administration, Association of the Bar of the City of New York (2001-2004)

*Information regarding the methodology utilized by Chambers and Partners can be found here.

*Information regarding the selection process undertaken by Super Lawyers can be found here.