William Dalsen is a partner in the Litigation Department and a member of the Asset Management Litigation Group. An experienced litigator and trial lawyer, Will focuses on complex commercial litigation and high-stakes trials with a particular emphasis on asset management, antitrust, healthcare and bankruptcy litigation.
Will has litigated a range of matters in federal courts across the country and in arbitration. He was a key member of the trial team that secured a complete defense verdict on behalf of Gilead Sciences, Inc., Gilead Holdings, LLC and Gilead Sciences, LLC in a $3.6 billion antitrust case on allegations that the pharmaceutical company struck an anticompetitive "pay-for-delay" patent settlement related to two HIV medications. He has also served as lead trial counsel and led every phase of the litigation process in matters nationwide.
Will routinely represents investment funds, fund sponsors, portfolio companies and their officers and directors, including in significant post-closing M&A disputes. He is highly regarded for his deep knowledge of the private credit and private investment fund industries as well as his ability to provide counseling and resolve disputes for both sponsors and portfolio companies.
Before joining Proskauer, Will served for two years as a law clerk to Judge Susan Phillips Read of the New York State Court of Appeals, drafting bench memoranda and assisting with opinions in a variety of civil and criminal matters. While in law school, Will was Editor-in-Chief of the Wisconsin Law Review and served as a judicial intern to the Honorable Shirley S. Abrahamson, Chief Justice of the Wisconsin Supreme Court.
Education
-
University of Wisconsin Law School, J.D.
-
Lawrence University, B.A.
cum laude
Admissions & Qualifications
- Massachusetts
- New York
Clerkships
- New York Court of Appeals - Hon. Susan Phillips Read
Court Admissions
- Supreme Court of the United States
- U.S. Court of Appeals, Federal Circuit
- U.S. Court of Appeals, First Circuit
- U.S. Court of Appeals, Second Circuit
- U.S. Court of Appeals, Ninth Circuit
- U.S. District Court, New York, Western District
- U.S. District Court, New York, Southern District
- U.S. District Court, Massachusetts
- U.S. District Court, Texas, Eastern District
Awards & Recognition
Chambers USA: Massachusetts: Litigation: General Commercial Up & Coming 2025-2026
Best Lawyers in America, Ones to Watch 2024-2027
Matters
Notable Representations and Victories Include:
- In re HIV Antitrust Litigation: Trial counsel for Gilead Sciences, Inc., Gilead Holdings, LLC, and Gilead Sciences, LLC in a $3.6 billion antitrust case defending against allegations that the pharmaceutical company struck an anticompetitive "pay-for-delay" patent settlement related to two HIV medications. A California federal jury deliberated for two days and delivered a full defense verdict.
- A wire manufacturer in an antitrust and false advertising suit against three major copper wire competitors.
- A private equity sponsor and its funds in defense of claims, including breach of fiduciary duty and aiding and abetting breach of fiduciary duty, related to the sale of a portfolio company for hundreds of millions of dollars (N.Y. Sup. Ct.)
- A private equity sponsor, together with its fund and partners, in defense of claims related to the liquidation of a portfolio company seeking more than $100 million (Del. Ch.) (Wis. Cir.)
- A private credit fund and several of its affiliates in defense of RICO and other claims in a putative class action related to alleged “payday lending” activities (E.D. Va.).
- A venture capital firm in defense of claims brought by a limited partner related to alleged failure to make timely distributions of fund assets and properly allocate carried interest (N.Y. Sup. Ct.).
- Financial Oversight and Management Board for Puerto Rico, in its own right and as debtors’ representative, in litigation related to the restructuring of the Commonwealth’s $74 billion of bond debt and $50 billion of unfunded pension obligations (D.P.R.) (Bankr. D.P.R.).
- EVEMeta, LLC v. Synacor, Inc. (N.Y. Sup. Ct.): Represented Synacor in a case alleging breach of contract and business torts relating to over-the-top content delivery services.
- ITW Global Investments, Inc. v. American Industrial Partners (Super. Ct. Del.): Represented AIP in a case relating to the acquisition of a manufacturer of advanced flow, pressure, and vacuum measurement and control devices.
- Oppenheimer Rochester High Yield Municipal Fund et al. v. Tobacco Settlement Financing Corporation (R.I. Super. Ct.): Represented a Rhode Island governmental issuer of tobacco settlement revenue backed bonds in defense of lawsuit brought by two municipal bond funds seeking to block proposed $600 million bond issuance. After expedited discovery, the court granted the issuer’s motion for summary judgment in all respects, permitting the bond issuance to proceed.
- Multiple fund sponsors in connection with SEC investigations into alleged pay-to-play and expense shifting violations and whether certain firm personnel are “covered associates.”
- A large European investment fund that lost approximately $400 million in various Madoff feeder funds.