• James Madison University (B.A., cum laude, 1999)
  • George Washington University Law School (J.D., 2002)


  • District of Columbia and Virginia
  • United States Supreme Court
  • United States Courts of Appeals for the Tenth, District of Columbia, and Federal Circuits
  • United States District Courts for the District of Maryland, Western District of Tennessee, Eastern District of Texas, and Eastern and Western Districts of Virginia


Ann Marie Duffy has broad experience in the defense of complex civil litigation, including commercial, construction, products liability, environmental tort, fraud, and intellectual property cases.  She has substantial trial and oral argument experience, having first-chaired two trials and second-chaired a patent trial in the District Court of Delaware in a case where total damages exceeded $2 billion.  Ms. Duffy has appeared and argued countless motions in state and federal courts nationwide.  In addition to her trial experience, she has also briefed and argued appeals to the United States Court of Appeals for the Tenth Circuit, the United States Court of Appeals for the District of Columbia Circuit, and the State of New York Supreme Court, Appellate Division Third Judicial Department.

Currently, she is trial counsel in defense of a series of personal injury trials in Cook County, Illinois circuit court arising from alleged exposure to ethylene oxide emissions from a medical device sterilization company. Her wide range of litigation experience includes working on highly complex cases with significant discovery and procedural issues.  Her cases have routinely involved multi-national discovery efforts and extensive, in-depth investigations.  She also has extensive experience conducting comprehensive due diligence investigations for corporate transactions and negotiating and preparing complex agreements that protect commercial interests and facilitate compliance with private corporate obligations and governmental requirements.

Ms. Duffy is currently defending a major engineering, procurement, and construction (EPC) contractor against alleged breach of contract, professional negligence, and fraud claims arising from the design, engineering, and construction of a nearly $1 billion agrochemical plant in Arkansas circuit court.  She will work as a trial team partner at the upcoming 10 to 12 week jury trial and, among other roles, will direct and cross fact and expert witnesses and argue evidentiary issues before the court.

Ms. Duffy is also lead counsel for a producer of PTFE and silicone-coated fabrics, tapes, and belts, defending against claims of negligence, trespass, and nuisance for its use and handling of materials containing trace amounts of PFOA in New York state court.  For several years she has lead the defense against claims that her client intentionally or negligently contaminated air and groundwater with PFOA.  She won summary judgment on claims asserting strict liability for intentional contamination and was successful in preventing expert testimony that PFOA is associated with some health conditions.  She also defended against claims of PFOS contamination in Michigan, which resulted in a successful resolution for her client.

Ms. Duffy is President of the National Catholic Forensic League and serves as the Washington Diocesan Director for the local affiliated league, the Washington-Arlington Catholic Forensic League.