Leslie O’Leary

Of Counsel

I believe in speaking truth to power. I also know the pen is mightier than the sword. My passion is giving voice to the vulnerable through written advocacy. I’ve devoted my entire career to holding wrongdoers accountable for the harms they inflict. But obtaining justice for clients is elusive without selflessness and collaboration with a brilliant, ethical, and fearless team. That’s why I am honored to be part of Ciresi Conlin. We all share the same mission to protect access to a justice system that treats those it serves with fairness and dignity.


Leslie specializes in product liability and mass tort litigation, representing plaintiffs harmed by defective pharmaceuticals, medical devices, and consumer products. She has extensive experience in state and federal court, including multi-district litigations. Leslie is nationally respected by her colleagues for writing and arguing briefs involving complex legal and scientific issues at all stages of litigation in courts throughout the country. She has also drafted appellate briefs before the Oregon Supreme Court, the Eighth and Ninth Circuits, and the U.S. Supreme Court.

Leslie was appointed to the eight-member national Plaintiff’s Coordinating Committee in Ephedra MDL and served on the Law & Briefing and Science committees in the PPA and Prempro MDLs. In addition, Leslie was part of the Law & Briefing and bellwether trial teams in the Bair Hugger MDL, writing Daubert and pretrial briefs, and assisted in drafting appeals to the Eighth Circuit opposing the exclusion of general-causation experts. She also serves on the Law & Briefing Subcommittee of the 3M Combat Earplugs MDL.

Before joining Ciresi Conlin in 2021, Leslie worked at Johnson Johnson Lucas & Middleton in Eugene, Oregon for five years, managing the firm’s mass tort practice. For the previous 17 years, Leslie was a partner at Williams Love O’Leary & Powers in Portland, where she practiced in the areas of products liability and mass tort litigation.

Leslie graduated from Lewis & Clark Law School in Portland, Oregon in 1998.  A Montana native, Leslie graduated cum laude from the University of Montana in Missoula with a bachelor’s degree in Political Science and minored in Spanish and History.

 Bar Admissions

  • Oregon
  • District of Oregon
  • S. Court of Appeals, Ninth Circuit
  • S. Supreme Court

Selected Case Results

In re Bair Hugger Forced Air Warming Devices Prods. Liab. Litig., MDL 2666: Serves on Plaintiffs’ Law & Briefing Committees.  Helped brief and defeat 3M’s initial Daubert, dispositive, and pre-trial motions. Helped successfully draft appellate briefs that led to the Eighth Circuit reversing the district court’s exclusion of expert testimony.  Nearly 6,000 plaintiffs’ suits were revived and are pending in the District of Minnesota.

In re Prempro Prods. Liab. Litig., MDL 1507*: Served on Plaintiffs’ Science & Experts and Law & Briefing Committees. Drafted and defeated defendants’ federal preemption and Daubert motions, drafted and argued pretrial motions in the MDL and in the New Jersey consolidated Prempro litigation. Developed expert witnesses; took and defended medical causation experts’ depositions.

In re Ephedra Prods. Liab. Litig., MDL 1598*: Appointed to eight-member national Plaintiffs’ Coordinating Committee. Chaired Law & Briefing subcommittee. Developed experts; drafted, argued, and defeated Defendants’ Daubert motions; drafted briefs on other miscellaneous issues.

In re Phenylpropanolamine (PPA) Prods. Liab. Litig., MDL 1407*: Served on Plaintiffs’ Science & Experts and Law & Briefing Committees.  Developed expert witnesses, took and defended expert depositions.  Drafted and defeated Daubert motions, discovery motions. Drafted, argued, and defeated motions to exclude expert testimony and pretrial motions in parallel state court litigation, resulting in settlement.

Lucas-Werner v. Novo-Nordisk AG, Multnomah Cnty., OR*: Represented plaintiff who developed breast cancer from menopausal hormone replacement therapy. Briefed, argued, and defeated Danish defendant’s motion to dismiss for lack of specific personal jurisdiction; briefed and defeated defendant’s mandamus petition to the Oregon Supreme Court; briefed and defeated defendant’s petition for certiorari before U.S. Supreme Court, leading to settlement following three years of litigation on jurisdiction issue.

Pain Pump Chondrolysis Litigation*: The MDL panel denied centralization of hundreds of lawsuits alleging improper marketing of pain pumps for use in orthopedic shoulder surgery that caused chondrolysis. Counsel for approximately 100 plaintiffs in state and federal jurisdictions across the country. Briefed, argued, defeated Daubert motions, summary judgment and preemption motions in multiple jurisdictions, as well as pretrial and post-trial motions and appeals in state and federal court consolidations in Oregon.

In re Diet Drugs Prods. Liab. Litig., MDL 1203*: Represented clients in parallel state court consolidated litigation in Oregon, successfully drafted and argued discovery, dispositive, pretrial motions. Served on Plaintiffs’ discovery committee, reviewed documents, took depositions.

*Case results before 2021 were achieved while Leslie was at a former firm.


  • Oregon Super Lawyers
  • Board Vice President, Oregon Jury Project
  • Former Board Governor of Oregon Trial Lawyers Association
  • Former Board Governor of Oregon Women Lawyers
  • Former Adjunct Professor, Lewis & Clark Law School

Community Service

Leslie is an active member of the American Association for Justice. In addition to presenting at AAJ legal education seminars, Leslie is a frequent guest lecturer at Oregon Health Sciences University and Lewis & Clark Law School.

She is also actively involved in reproductive rights advocacy.  For several years, she served on the Board of NARAL Pro-Choice Oregon and was Board President in 2015-2016.



  • Author, “Build a Better Road Map – Drafting Rule 26 Expert Reports,” AAJ Trial Magazine , June 2021
  • Contributor, “Product Liability” and “Wrongful Death,” Oregon Statutory Time Limits, OSB Professional Liability Fund (2021)
  • Author, “Protecting Rights and Access – NARAL,” OTLA Trial Lawyer, Spring 2020
  • Author, “Causation – The Key to Medical Products Cases,” OTLA Trial Lawyer, Winter 2014
  • Co-Author, Chapter 21, “Mass Torts,” Torts (2012 rev.), OSB Legal Publications, Sept. 2012
  • Author, “Litigating in the Absence of an MDL,” AAJ Trial Magazine, Nov. 2010
  • Contributor, “Product Liability” and “Wrongful Death,” Oregon Statutory Time Limitations (2010 rev.) OSB Professional Liability Fund, July 2010
  • Author, Chapter 25, “Experts,” Federal Civil Litigation in Oregon (2009 rev.), OSB Legal Publications, Oct. 2009
  • Author, “Does FDA Regulation of Drug Labeling Preempt State Law Failure to Warn Claims?” OSB Products Liability Newsletter, Spring 2007
  • Author, “In Pursuit of Ephedra: The Challenges of Pharmaceutical Mass Torts,” OTLA Trial Lawyer, Spring 2006
  • Co-Author, “The Fraud of Hormone Therapy: How Drug Companies Manipulated Women,” OTLA Trial Lawyer, Spring 2006
  • Author, “Less than Perfect Evidence: The Collision of Science and Law under Daubert,” OSB Products Liability Newsletter, Winter 2006
  • Author, “Pharmaceutical Mass Torts: A High Stakes Game,” OTLA Trial Lawyer, Winter 2002
  • Author, “Kumho Tire in Oregon: Should it Apply?” OTLA Trial Lawyer, Summer 2000
  • Author, “Mass Tort Class Actions: Will Amchem Spawn Creative Solutions?” Defense Counsel Journal, Oct. 1998 (First Prize Winner, Writing Competition).