sentences:  In this context, evergreening may be used by manufacturers of a particular drug to restrict or prevent competition from manufacturers of generic equivalents to that drug.In 2002, an extensive and lengthy inquiry by the US Federal Trade Commission (FTC) found, in the wake of the Hatch-Waxman legislation or Drug Price Competition and Patent Term Restoration Act (which was instrumental in establishing the US generic pharmaceuticals industry), as many as 75% of new drug applications by generic drug manufacturers had been contested with legal actions under patent laws by the original brand name patent owner.These were driving up US drug costs by keeping the cheaper generic versions off the market.