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Kathleen M. O'Sullivan

Profile photo for Katie O'Sullivan
Profile photo for Katie O'Sullivan
Partner

Kathleen M. O'Sullivan

A veteran litigator and community leader, Katie helps businesses with critical legal matters.

With more than 25 years of practice, Katie O'Sullivan represents businesses facing high-stakes litigation, including trial court cases and appeals. She regularly advises Fortune 100 and other leading companies across industries in consumer class actions, pending investigations, and other related cases. Katie also works on appeals across a broad spectrum of legal issues, including antitrust, contracts and business torts, environmental law, product labeling, privacy, and product liability.

Katie emphasizes high-quality written and oral advocacy in her litigation practice and as a leader in the firm. Katie served as the chair of the firm's Executive Committee from 2020 through 2023, during which time she led the development of the firm's strategic plan. She is also the former firmwide chair of the Commercial Litigation practice.

Katie is an active member of the legal community and has served on the Washington State Bar Association Board of Governors and chaired the Washington State Commission on Judicial Conduct. Katie currently serves on the American Law Institute Council and the Ninth Judicial Circuit Historical Society board. She is a former chair of the Board of Directors of the YMCA of Greater Seattle.

Education & Credentials

Education

  • Georgetown University Law Center, J.D., cum laude, Senior Notes Editor, Georgetown Law Journal
  • Yale University, B.A., History, cum laude

Bar and Court Admissions

  • Washington
  • Supreme Court of the United States
  • U.S. Court of Appeals for the Fourth Circuit
  • U.S. Court of Appeals for the Sixth Circuit
  • U.S. Court of Appeals for the Seventh Circuit
  • U.S. Court of Appeals for the Ninth Circuit
  • U.S. District Court for the Eastern District of Washington
  • U.S. District Court for the Western District of Washington

Related Employment

  • Miller Cassidy Larroca & Lewin, Washington, DC, Summer Associate, 1996
  • Perkins Coie, Seattle, WA, Summer Associate, 1995
  • DNA – People’s Legal Services, Window Rock, Navajo Nation, AZ, Law Clerk, 1994

Clerkships

  • Kathleen M. O'Sullivan > Clerkships, U.S. District Court for the District of Columbia
  • Kathleen M. O'Sullivan > Clerkships, U.S. Court of Appeals for the Ninth Circuit

Professional Recognition

  • Listed in Chambers USA as "America’s Leading Litigation Lawyer" 2018-2024

  • Named Best Lawyers "Lawyer of the Year" for Appellate Practice, 2016, 2024; for Bet-the-Company Litigation, 2025

  • Listed in Best Lawyers in America: Appellate Practice; Bet-the-Company Litigation; Commercial Litigation, 2009-2025

  • Listed in Super Lawyers Magazine, “Washington's Super Lawyers," 2007-2023

  • Co-Recipient of awards for IOLTA Supreme Court litigation (American Bar Association, Washington State Bar Association, King County Bar Association, Perkins Coie)

Impact

Professional Leadership

  • Ninth Judicial Circuit Historical Society, Board Member, 2017-present
  • Elected to governing Council of American Law Institute (2015); member of American Law Institute since 2006
  • Washington Commission on Judicial Conduct, Lawyer Member, 2007-2015; Chair, 2012-2014
  • Ninth Circuit Appellate Lawyer Representative, 2010-2013
  • Federal Bar Association for the Western District of Washington, Chair of Appellate Practice Committee, 2007 and 2008
  • Washington State Bar Association, Board of Governors, 2003-2006

Community Involvement

  • YMCA of Greater Seattle, Board Chair (former); Executive Committee member (former); Board member, 2011-present
  • Perkins Coie Campaign for United Way of King County, Chair, 2009-2012 
  • Leadership Tomorrow, Class of 2009
  • Passages Northwest, Board Member, 2000-2003

Professional Experience

Appellate

Georgia-Pacific Consumer Products LP v. NCR Corp., et al.

U.S. Supreme Court
U.S. Court of Appeals for the Sixth Circuit
Successfully argued for reversal of district court’s judgment on a CERLA limitations issue; defeated petition for rehearing en banc; defeated petition for certiorari. 32 F.4th 534 (6th Cir. 2022); 40 F.4th 481 (6th Cir. 2022); 144 S.Ct. 69 (2023)

Global BTG LLC v. National Air Cargo Inc.

U.S. District Court for the Central District of California, U.S. Court of Appeals for the Ninth Circuit
Represented the plaintiff Global BTG, an aircraft financing company, in a case arising out of the parties’ agreement involving the financing of eight commercial aircraft. The Ninth Circuit affirmed the judgment that had resulted from a jury verdict in favor of Global BTG on its breach-of-contract claim against National Air Cargo, ruling that the jury was properly instructed and that the jury damages award was supported by substantial evidence. A video of the argument is available here. 2016 WL 2811591 (9th Cir.).

Maple v. Costco Wholesale Corporation

U.S. District Court for the Eastern District of Washington, U.S. Court of Appeals for the Ninth Circuit
Represented Costco in the trial court and on appeal. Obtained dismissal of first and second amended complaints for failure to state a claim. The district court found the plaintiff’s allegations of deception in the name of the product “VitaRain” to be implausible, and also concluded that the plaintiff had failed to adequately plead causation of any injury. The Ninth Circuit affirmed. 2016 WL 2621345 (9th Cir.), 2013 WL 5885389 (E.D. Wash.)

Reinking v. Alyeska Pipeline Services Co.

U.S. District Court for the District of Alaska, U.S. Court of Appeals for the Ninth Circuit
Represented Alyeska and its pension and benefits plans on appeal. Obtained reversal of summary judgment in favor of plaintiff. The Ninth Circuit ruled that the plan administrators did not abuse their discretion in denying application for benefits. 539 Fed. Appx. 780 (9th Cir. 2013).

Brown v. Legal Foundation of Washington, et al.

U.S. District Court for the Western District of Washington, U.S. Court of Appeals for the Ninth Circuit, U.S. Supreme Court
Defeated constitutional challenge to Interest on Lawyer Trust Account (IOLTA) program that provides substantial funding for legal aid programs nationwide. Supreme Court affirmed that such programs are not unconstitutional. 538 U.S. 216 (2003), aff'd 271 F.3d 835 (9th Cir. 2001) (en banc).

Dex Media West Inc. v. City of Seattle

U.S. District Court for the Western District of Washington, U.S. Court of Appeals for the Ninth Circuit
Obtained the reversal of a district court decision and award of injunction against an ordinance requiring distributors of Yellow Pages directories to register with and obtain a permit from the city, pay a fee for each book they distribute, participate in a city-run delivery opt-out program, and advertise the opt-out program on the front cover of each directory they distribute. The Ninth Circuit concluded that Yellow Pages directories qualify for full protection under the First Amendment and that the ordinance was unconstitutional because it was not the most narrowly tailored means of achieving the city’s objectives. 696 F.3d 952 (9th Cir. 2012).

Getz v. The Boeing Company

U.S. District Court for the Northern District of California, U.S. Court of Appeals for the Ninth Circuit
Obtained a Ninth Circuit decision, in a wrongful death action arising out of a helicopter crash in Afghanistan, affirming summary judgment for Boeing and other manufacturers on the basis of the government-contractor defense. Persuaded court that the manufacturers could not be subject to tort liability where they had complied with the precise design specifications approved by the Army. 654 F.3d 852 (9th Cir. 2011).

Judd v. AT&T

King County Superior Court (Washington), State Court of Appeals of Washington, State Supreme Court of Washington
Represented defendant Qwest in putative class action regarding disclosure of rates for long-distance telephone calls by Washington State prisoners. Won dismissal of claim and affirmance of that judgment on appeal. 66 P.3d 1102 (Wash. Ct. App. 2003), aff'd, 95 P.3d 337 (Wash. 2004) .

King v. King

State Supreme Court of Washington
Pro bono representation on appeal. In "civil Gideon" case, argued – ultimately unsuccessfully – that the trial court should have appointed counsel to defend our client (an indigent woman who could not afford counsel) in a child custody proceeding in which she faced the loss of her fundamental parenting rights and her opponent (her then-husband) was represented by counsel. 174 P.3d 659 (Wash. 2007).

McCarthy Finance, Inc., et al. v. Premera, et al.

King County Superior Court (Washington)
State Court of Appeals of Washington
State Supreme Court of Washington
Represented defendant Washington Alliance for Healthcare Insurance Trust and its trustee in putative class action regarding challenge to reasonableness of health insurance rates. Won dismissal of claim and unanimous reversal of adverse Court of Appeals decision. 328 P.3d 940 (Wash. Ct. App. 2014), rev’d, 347 P.3d 872 (Wash. 2015).

Shillinger v. Highline School District

State Court of Appeals of Washington
Represented school district on appeal. Obtained reversal and new trial following jury verdict for plaintiff alleging occupational mold disease. 2008 WL 2174436 (Wash. Ct. App.)

Turek v. General Mills Inc.

U.S. Court of Appeals for the Seventh Circuit
Obtained affirmance of the dismissal of a putative class action against our client, General Mills, on grounds that the plaintiff’s deceptive advertising claims were preempted by the Nutrition Labeling and Education Act, which sets forth uniform standards for food labeling. 662 F.3d 423 (7th Cir. 2011).

Litigation

Alaska Spine Center, LLC v. Mat-Su Valley Medical Center, LLC, et al.

Supreme Court of Alaska
The Alaska Supreme Court unanimously upheld summary judgment in favor of our ambulatory surgery center client in its challenge to the State of Alaska’s grant of an exemption to Alaska certificate-of-need laws to an Anchorage-based surgical facility that sought to relocate from Anchorage to Wasilla. (2019 WL 1416034.)

Move, Inc. v. Zillow, Inc.

King County Superior Court (Washington)
Represented the defendant Zillow in an employment-related unfair competition/ trade secrets case against its largest competitor in which the plaintiffs sought approximately $2 billion in damages. After the Court dismissed more than $1 billion of plaintiffs’ claimed damages, found in favor of Zillow on allegations of spoliation, and granted several of the client’s motions for partial summary judgment including dismissal of most of plaintiffs’ tort-based claims, case settled on what was scheduled to be the first day of trial.

Borders, et al. v. King County, et al. and Washington State Democratic Central Committee

Superior Court of Washington, Chelan County
Challenge to the election of Washington State Governor Christine Gregoire, the closest gubernatorial election in United States history. After two-week trial, the court upheld the election results.

City of Livonia Employees' Retirement System v. The Boeing Company

U.S. District Court for the Northern District of Illinois, U.S. Court of Appeals for the Seventh Circuit
Represented Boeing and two of its senior executives in a securities fraud class action relating to the delay of first flight of the 787 Dreamliner. Plaintiffs' operative complaint relied on the alleged statements of a confidential source who purportedly possessed high-level knowledge. After plaintiffs revealed the identity of their source, defendants secured a declaration and deposition from the source, in which he refuted the allegations attributed to him. Defendants subsequently moved for and won dismissal of plaintiffs' complaint with prejudice. The court agreed with defendants that plaintiffs' counsel failed to conduct a reasonable inquiry and made material misrepresentations of fact concerning the source's position and personal knowledge. Plaintiffs appealed and defendants cross-appealed seeking sanctions under the Private Securities Litigation Reform Act. The court affirmed dismissal and remanded for consideration of sanctions. District court awarded all of Boeing's reasonable defense fees and costs as sanction against plaintiffs' counsel. 711 F.3d 754 (7th Cir. 2013).

Election Systems & Software, LLC v. Pierce County

Pierce County Superior Court (Washington)
Secured permanent injunctive relief for election software provider under Washington’s Public Records Act. Injunction prevented county auditor from publicly disclosing confidential and trade secret documents relating to the functionality of election software.
 

Fultz v. World Savings & Loan Association

U.S. District Court for the Western District of Washington
Represented National City Bank and National City Mortgage Company in defense of "predatory lending" claim. Won dismissal of myriad of state law claims on basis of federal preemption. 2008 WL 4131512 (W.D. Wash. 2008).

In re Cheerios Marketing & Sales Practices Litigation

U.S. District Court for the District of New Jersey
National counsel for General Mills in defense of putative class actions alleging false and deceptive marketing of the health benefits of Cheerios. Obtained summary judgment dismissal of most of the individual plaintiffs' claims for failure to establish any damage, and summary judgment dismissal of the class action allegations of the remaining plaintiffs.

Pharmaceutical Industry Average Wholesale Price Litigation

U.S. District Court for the District of Massachusetts
State courts in Alabama, Alaska, Arizona, Illinois, Iowa, Kansas, Kentucky, Mississippi, New Jersey, New York, Pennsylvania, and Wisconsin.
National coordinating and trial counsel in defense of nationwide consumer protection class action, parens patriae, antitrust and false claims act challenges to pharmaceutical pricing.
431 F. Supp. 2d 98 (D. Mass. 2006); 339 F. Supp. 2d 165; 321 F. Supp. 2d 187; 309 F. Supp. 2d 165; 307 F. Supp. 2d 196 (D. Mass. 2004); 230 F.R.D. 61 (D. Mass. 2005).

Trinity Glass International Inc. v. LG Chem Ltd.

U.S. District Court for the Western District of Washington
Defense of international chemical company in $50 million breach of contract, breach of warranty and fraud case involving polymer resin. Case settled on first day of trial. Court granted client’s motion for partial summary judgment dismissing more than $25 million of plaintiffs’ claimed damages and dismissing all of plaintiffs’ tort-based claims.

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