Arnold & Porter Secures Precedential Tenth Circuit Victory for AstraZeneca in PREP Act Immunity Case

Arnold & Porter secured a precedential victory for AstraZeneca before the U.S. Court of Appeals for the Tenth Circuit, obtaining reversal of a district court decision in a case presenting a question of first impression regarding the scope of immunity under the Public Readiness and Emergency Preparedness (PREP) Act.

In Dressen v. AstraZeneca AB, No. 24-4114 (10th Cir. 2026), the plaintiff, a participant in AstraZeneca's COVID-19 vaccine clinical trial, brought a breach of contract claim after the company denied her request for reimbursement of injury-related costs under her informed consent agreement. The district court held that the PREP Act's immunity provision applied only to tort claims. In a unanimous, 38-page published opinion, the Tenth Circuit reversed, holding that the statute's reference to "claims for loss" extends to contract claims and therefore bars the plaintiff's suit.

The court also accepted the firm's collateral-order doctrine argument, concluding that immediate appellate review was appropriate because AstraZeneca's statutory immunity from suit would otherwise be irretrievably lost. The case was remanded solely to consider whether AstraZeneca contractually waived its immunity.

The Arnold & Porter team was led by partners Reeves Anderson, Arthur Brown, and Alexander Cousins, and senior associate Sam Ferenc.