inequitable conduct in the procurement or enforcement of a patent (sometimes termed "non-purgeable misuse").
In the United States, a patent is a statutory right that grants the patentee the right to exclude others from making, using, or selling a patented invention. <!-- ] Historically, courts were willing to entertain a patent misuse defense for patent owners who never undertook any commercial use and solely sought out infringers. Recent decisions have held --> Under current U.S. patent law it is not patent misuse simply to enforce rights to a patent, in good faith, and enforcement is permissible irrespective of any use or non-use by the owner.See 35 U.S.C. § 271(d)(4); Dawson Chemical Co. v. Rohm & Haas Co., 448 U.S. 176 (1980). "Sham" or bad-faith patent enforcement--i.e., without belief that the claim is meritorious--however, can give rise to liability. See Professional Real Estate Investors, Inc. v. Columbia Pictures Industries, Inc., 508 U.S. 49 (1993).