O’Melveny Worldwide


“Hannah is creative and an excellent writer. She’s a great lawyer to the business who is really dedicated to her clients.”

 “She’s responsive and a good sounding board. I trust her opinions and value her advice.”

—Client Testimonials, Chambers USA 2024

As Co-Chair of O’Melveny’s Consumer Class Actions Practice, Hannah Chanoine focuses on defending and advising companies in a diverse range of class action matters in the trial and appellate courts.

Hannah began her career clerking for the Hon. Sonia Sotomayor on the Second Circuit Court of Appeals, and then served as a trial attorney in the Department of Justice, Civil Division (Federal Programs Branch) through the Attorney General’s Honor’s Program. Hannah received her JD from Columbia University School of Law, where she was twice named a James Kent Scholar for outstanding academic achievement. Hannah is currently a member of the adjunct faculty at Columbia Law School, where she co-teaches a course on US Food Law and Policy.

  • Defending and advising consumer packaged goods companies in nationwide false advertising cases. Hannah has represented leading manufacturers and retail distributors of toothpaste, sunscreen, skin moisturizers, OTC pain and cold medicines, bottled water, coconut water, deodorant, shampoos and conditioners, lactase supplements, infant formula, therapeutic and wellness pet foods, household cleaners, nutraceuticals, flavored olive oil, Greek yogurt, kombucha, baking products, probiotic baby food, juice beverages and many other consumer products. Hannah counsels CPG clients up and down the supply chain on strategies for mitigating class action litigation risk during product and label development, and advises investors conducting due diligence on the class action litigation risk profiles posed by potential targets.
  • Lead defense of portfolio wide class action threats to leading manufacturers of: “natural” toothpaste and deodorants, “oil free” moisturizers, “non-drowsy” cold medicines, and “prescription” pet foods.
  • Lead defense counsel in MDL consolidating dozens of consumer class actions following global recall of tainted pet food.
  • Defeated class certification in case seeking US$300+ million in statutory damages under NY GBL 349, 350 over trans-fat labeling of cholesterol lowering spread.
  • Lead defense counsel defeating labeling claim in district court and on appeal against leading lactase supplement manufacturer on preemption grounds.
  • Lead defense counsel defeating multiple motions to dismiss “100% Recyclable” claims against leading spring water manufacturer.
  • Defending leading HD television distributor in nationwide class action alleging deceptive marketing relating to energy efficiency.
  • Defending a major satellite radio broadcaster in class action lawsuit alleging over US$1 billion in damages for violations of novel intellectual property rights.
  • Defending products manufacturer against class action claim based on novel tort theory seeking comprehensive injunctive relief valued at over US$200 million.
  • Serving as counsel for trade associations and business oriented advocacy groups as amici curiae addressing cutting edge class action issues in federal courts of appeal and the U.S. Supreme Court.
  • Serving as legal strategy counsel for Fortune 200 consumer products company in 15 jury trials tried to verdict or mistrial, including individual and mass actions, each seeking millions of dollars in compensatory and/or punitive damages.
  • Defending Department of Interior against class action claims alleging hundreds of millions of dollars of damages for breached contracts.
  • Writing merits and amicus briefs addressing a broad range of substantive and evidentiary issues in state and federal appellate courts nationwide, including the US Supreme Court and state supreme courts, and arguing multiple times before the Second Circuit Court of Appeals.
  • Lead responsibility for defending federal agencies in federal and state courts nationwide, including the Treasury Department’s Office of Foreign Assets Control and the State Department’s Foreign Service.
  • Maintaining an active pro bono practice. Hannah has worked closely with the ACLU and other civil rights organizations on LGBT rights, including: filing a lawsuit in Wisconsin to vindicate the rights of more than 500 same-sex couples that had married following a federal court ruling striking down that state’s marriage ban, but where the state refused to recognize the marriages, successfully persuading the state to change their position; filing amicus briefs in two “refusal of service” cases in the Colorado and New York appellate courts, advocating for robust enforcement of those states’ anti-discrimination laws on behalf of LGBT couples who had been denied services because of their orientation; and filing amicus briefs in the US Supreme Court and the Eighth Circuit cases addressing marriage equality. Hannah recently served a three-year term appointment to the Second Circuit Court of Appeals Pro Bono Panel.


Bar Admissions

  • New York
  • Massachusetts 

Court Admissions

  • US Supreme Court
  • US District Court, Northern District of Florida, Middle District of Georgia, Central District of Illinois, Eastern District of Michigan, and Eastern and Southern Districts of New York
  • US Court of Appeals, First, Second, Third, Sixth, Seventh, Ninth, and Eleventh Circuits
  • United States Court of Federal Claims


  • Columbia Law School, JD, 2004; Winner: 2004 Columbia Law Review Publishable Notes Competition, James Kent Scholar (2002-2003 and 2003-2004)
  • Wellesley College, BA, magna cum laude, 1998; Economics, Phi Beta Kappa

Honors & Awards

  • Recognized by Chambers USA for Litigation: General Commercial (2024)
  • Recommended by The Legal 500 US for General Commercial Disputes (2020); Product Liability, Mass Tort and Class Action - Defense: Consumer Products (Including Tobacco) (2021-2022, 2024); Product Liability, Mass Tort and Class Action - Defense: Automative/Transport (2024); Product Liability, Mass Tort and Class Action - Defense: Pharmaceuticals and Medical Devices (2022 & 2024); Product Liability, Mass Tort and Class Action - Defense: Toxic Tort (2024)
  • Client Service All-Stars BTI Consulting (2020, 2023)
  • Crains New York Business - Notable Women in Law (2022)

Professional Activities


  • Honorable Sonia Sotomayor, US Court of Appeals, Second Circuit

Faculty Member

  • Columbia University School of Law, Lecturer-in-law, US Food Law & Policy (2016-present)


  • American Bar Association: “27th Annual National Institute on Class Actions,” Chicago (October 19, 2023) (Moderator: Aggregated Statutory Penalties)
  • American Bar Association: “26th Annual National Institute on Class Actions,” Scottsdale (November 10, 2022) (“How Much Evidence Is Enough At Class Certification?”)
  • ACI “Class Action Strategies: Evolving Theories, Defense Tactics, and Resolutions” (July 15, 2020)
  • ACI Advanced Food Law and Marketing Symposium: “Class Action Strategies: Practical Pointers for Avoiding and Resolving Claims in Light of Plaintiff Bar’s Continuously Evolving Theories,” New York (April 1, 2020)
  • Michigan State University Institute for Food Laws and Regulations, Global Food Law Current Issues Conference 2018, “Managing Class Action Litigation Risk - Label Workshop,” East Lansing (June 20, 2018)
  • OMM CLE Marathon: “Good Corporate Citizenship Efforts: CSR and Pro Bono”, New York (May 16, 2018)
  • ACCP Annual Conference 2018: “When to Check with Legal: Navigating Complex CSR Waters,” Portland (March 19, 2018)
  • GMA Legal Conference 2018: “It’s Raining Cats and Dogs: Increasing Litigation Against Pet Food Companies” New Orleans (February 28, 2018)
  • Conference Co-Chair: ACI Defending and Managing Class Actions Conference, New York (April 3-4, 2017)
  • CLE International, Food Law: The Evolving Food Law Landscape Conference, “Hullabaloo about Healthy: Nutrition Bars, Total Fat, and the Like,” Austin (May 11-12, 2017)
  • PLI 22nd Annual Consumer Financial Services Institute, “Class Action Developments and Settlements,” Chicago (May 4, 2017)
  • ACI Defending and Managing Class Actions Conference, “Tackling the Unique Ethical Considerations in Class Actions CLE," New York, (April 3-4, 2017)
  • GMA Legal Conference 2017: “Lessons Personal Care and Household Product Companies can Learn from Food Industry Litigation Battles,” San Diego (February 27-28, 2017)
  • FDLI Food Advertising, Labeling and Litigation Conference, “Litigation Proofing, Litigation Strategy, and Risk-Management,” (September 15, 2016)
  • Michigan State University: Food Law Current Issues Conference, “Food Law Litigation Landscape: Trends and Emerging Legal Risks,” (July 12-14, 2016)
  • WeiserMazars Food and Beverage Industry CFO Bootcamp “Investing in Food & Beverage Companies: Assessing a Target company’s Litigation Risk Profile During Due Diligence,” (June 15, 2016)
  • PLI 21st Annual Consumer Financial Services Institute, “Class Action Developments and Settlements,” Chicago (May 12, 2016)
  • PLI 21st Annual Consumer Financial Services Institute, “Class Action Developments and Settlements,” New York (April 4, 2016)
  • CLE International Food Law Conference, “Trans Fat: Not ‘Generally Recognized as Safe,’” (March 17-18, 2016)
  • FDLI Food Advertising and Litigation Conference, “Insights into the Food Court and Key Cases,” (September 24, 2015)


  • “Companies Face Demand for Third-Party CSR Certifications,” CFO.com (November 26, 2019)
  • “Managing Investor Risk in Food and Beverage Industry,” New York Law Journal (September 8, 2016)
  • “Hain Celestial ‘Natural’ Case Could Set Precedent Favorable To Industry,” Pharma & MedTech Business Intelligence’s, The Rose Report (April 16, 2015)
  • “Non-Capital Stay Applications In The United States Supreme Court: A Procedural Primer,” Certworthy (2010)
  • “Clarifying the Joint Action Test for Media Actors When Law Enforcement Violates the Fourth Amendment,” 104 Columbia Law Review 1356 (2004)


  • Federal Bar Council: Second Circuit Courts Committee, Inn of Court


  • Chair, Federal Bar Council Foundation