Image: Mary Walser

Mary Walser

Associate, Litigation Department


Mary Hamner Walser is an associate in the Litigation practice of Paul Hastings and is based in the firm’s Washington, D.C. office. She represents clients in antitrust and competition-related matters including merger and acquisition approval under the Hart-Scott-Rodino Act and state and federal antitrust litigation matters. Ms. Walser has represented clients in numerous industries, including health care, information technology, agriculture, transportation, telecommunications, and media. She received her law degree from the William and Mary School of Law, cum laude, in 2012. Ms. Walser earned a Bachelor of Arts degree in Economics from the University of Virginia in 2006. She is admitted to practice law in Virginia and the District of Columbia.


  • David H. Murdock and Dole Food Company in the sale of a 45% stake to Total Produce.
  • A leading containership operator in an ongoing grand jury investigation focused on price fixing/bid rigging in the shipping industry.
  • Samsung Electronics in the international merger control review of its $8 billion acquisition of Harman International industries, Inc.
  • Putative class of consumer packaged goods companies against dominate provider of in-store promotion and free-standing insert coupons.
  • American Airlines in connection with the DOJ antitrust review and challenge to the merger between American Airlines and US Airways.
  • Gannett Co., Inc. in connection with antitrust review of its merger with Belo Corp., a leading broadcast television company, a transaction valued at approximately $2.2 billion.
  • Jack Cooper Holdings Corp. in the antitrust review of its bankruptcy acquisition of competitor Allied Systems Holdings, a deal valued at $135 million, creating North America’s largest auto transportation company.
  • MetroPCS Communications in the antitrust review of its reverse merger with T-Mobile USA, valued at over $10 billion.
  • LG Display in price-fixing civil litigation brought by individual purchasers and state attorneys general in federal and state courts regarding the TFT-LCD flat panel display components.

Engagement & Publications

  • Michael Wise and Mary Walser, Taking Stock of Antitrust Efforts Targeting Private Equity, Wall Street Lawyer, Volume 27, Issue 11 (November 2023)
  • Ms. Walser is a co-author of Responding to Federal Corporate Criminal Investigations, a desk reference for defense counsel and corporate executives on responding to federal government investigations, and developing proactive strategies to prevent and mitigate corporate criminal liability.
  • Breaking the Glass Ceiling: Women in the Boardroom, A Study of Major Global Changes (2014)
  • Lee F. Berger and Mary H. Walser, "New Faces on the Bench: Profile of District Judge Haywood Gilliam," Antitrust and Unfair Competition Law E-Brief (State Bar of California) (February 2015)
  • "Executive Summary: Panel Summaries from FTC-DOJ Workshop on Examining Health Care Competition, February 24-25, 2015," American Health Lawyers Association Weekly (March 2015)
  • Michael S. Wise, Noah B. Pinegar, and Mary H. Walser, U.S. Merger Control in the High-Technology Sector, The Merger Control Review – 11th Edition (Aug. 2020)

Practice Areas


Antitrust and Competition




District of Columbia Bar

Virginia Bar


College of William & Mary, Marshall-Wythe School of Law, J.D. 2012

University of Virginia, B.A. 2006

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