of generic equivalents to that drug. Robin Feldman has documented several types of patent tactics commonly used in the U.S. by pharmaceutical companies, including evergreening, pay-for-delay, gaming the citizen petition process, and the misuse of trade secrets, among others. In one study of the prescription drug market, Feldman found that 78% of new patents associated with prescription drugs were for existing drugs.

In 2002, the US Federal Trade Commission