Williams & Connolly was lead counsel for AstraZeneca in what Bloomberg called a "landmark" class action antitrust litigation case related to AstraZeneca’s prescription heartburn medication Nexium®. The plaintiffs alleged that AstraZeneca and certain generic pharmaceutical companies violated federal and state antitrust laws when they settled Hatch-Waxman patent cases that AstraZeneca had brought to enforce its patents for Nexium®. Nexium® is a widely prescribed proton-pump inhibitor with annual U.S. sales in the billions of dollars. The case, involving issues of antitrust law, patent law, and food and drug law, is one of the first so-called "reverse-payment settlement" cases following the Supreme Court's ruling in FTC v. Actavis, 570 U.S. 756 (2013), in which the Court held that alleged "pay-for-delay" settlements may be challenged under federal antitrust laws. The case was tried before a Massachusetts federal jury starting in October 2014 and on December 5, 2014, after less than two days of deliberations, the jury returned a verdict in favor of AstraZeneca and its co-defendant, Ranbaxy Laboratories, on all counts.

On November 21, 2016, the United States Court of Appeals for the First Circuit affirmed the jury’s verdict in favor of AstraZeneca.  The jury found that the plaintiffs had not shown that they had suffered an antitrust injury that entitled them to damages.

The team representing AstraZeneca included Dane Butswinkas, Kannon Shanmugam, John Schmidtlein, Paul Gaffney, Jonathan Pitt, Stanley Fisher and Benjamin Greenblum.