Geoffrey M. Sigler is a partner in Gibson, Dunn & Crutcher's Washington, D.C. office. He practices in the firm's Litigation Department, and he is a member of the Firm’s Class Action, FDA and Health Care, Insurance and Reinsurance, Information Technology and Data Privacy, and White Collar Defense and Investigations Practice Groups.

Mr. Sigler has represented corporate clients in dozens of class actions and other complex litigation matters in federal and state courts throughout the United States. Mr. Sigler has obtained dismissal, summary judgment, and denial of class certification in cases involving a broad range of legal theories, including RICO, ERISA, the Sherman Act, and various state-law theories.

In recognition of Mr. Sigler’s repeated successes in major litigation matters, in 2013 Mr. Sigler was named one of Law 360’s Rising Stars – one of the nation’s top lawyers under 40 for Insurance.
Representative matters include:

Brink v. XE Holding, LLC (D.D.C.), a nationwide class action brought by employees of government contractors under RICO and various other legal theories, seeking $2 billion in damages from insurers and government contractors for the alleged mishandling of workers’ compensation claims. Mr. Sigler helped his client, a major insurer, obtain complete dismissal of all claims.
AHIP v. Hudgens (N.D. Ga.), a legal challenge to a Georgia state “prompt pay” law brought by Mr. Sigler’s client, a trade association representing administrators of health benefits plans. Mr. Sigler helped his client obtain a preliminary injunction blocking enforcement of the challenged law.
In re Aetna UCR Litigation, MDL 2020 (D.N.J.), a consolidated multi-district litigation in which putative nationwide classes of providers and subscribers allege that various managed care companies conspired to underpay plan benefits for out-of-network services. Claims are brought under RICO, the Sherman Act and ERISA.
In re Managed Care Litigation, MDL 1334 (S.D. Fla.), a consolidated multi-district litigation involving allegations of an industry-wide RICO conspiracy by managed care companies to deny, delay, and diminish payments to providers through claim editing software, provider contracting, and other practices.
Casey v. International Paper Company (N.D. Fla.), in which hundreds of property owners brought a class action claiming that the defendant contaminated their properties through the release of fly ash containing arsenic from a local plant.
Henry v. St. Croix Alumina (D. V.I.), in which thousands of property owners brought a putative class action based on allegations that their properties were contaminated by “red mud” released during Hurricane Georges.
Peterson v. Aetna (S.D.N.Y.), a lawsuit that arose out of a dispute between the acquiring company and the sellers over the purchase price and valuation of the acquired company. Mr. Sigler spearheaded a counterclaim strategy by which the acquiring company, the defendant, sought damages from the sellers, who were the plaintiffs, based on breaches of representations and warranties.

Mr. Sigler also has represented corporate clients, audit committees, and individuals in governmental and internal investigations. Mr. Sigler has successfully resolved investigations by the United States Department of Justice, the Securities and Exchange Commission, state attorneys general, and other federal and state regulators into a wide range of business and accounting practices. Mr. Sigler is a co-author of "Audit Committee Oversight of a Major Independent Investigation," Review of Securities & Commodities Regulation (Aug. 15, 2007). Mr. Sigler also has represented Medicare Advantage plans in connection with payment recovery audits by the Centers for Medicare and Medicaid Services.
Mr. Sigler graduated from the University of Virginia School of Law in 2001, where he was Articles Development Editor of the Virginia Journal of Social Policy and the Law. He received his Bachelor of Arts degree magna cum laude from the University of Richmond in 1998. Mr. Sigler is a member of the bars of the District of Columbia and Virginia.