The doctrine of patent licensee estoppel would prevent a patent licensee from asserting that a drug patent was not valid unless the licensee breached the patent license agreement and risked a lawsuit by the patent holder for willful patent infringement. The U.S. Supreme Court held in Medimmune v. Genentech that the doctrine was inconsistent with intent of the Hatch-Waxman Act and public policy to increase competition and decrease the costs of drugs to the benefit of the consumer. The prior positions of patent licensees, the Hatch-Waxman act, and the cases following Medimmune v Genentech are also analyzed..