In United States patent law, utility is a patentability requirement. As provided by 35 U.S.C. § 101, an invention is "useful" if it provides some identifiable benefit and is capable of use. The majority of inventions are usually not challenged as lacking utility, but the doctrine prevents the patenting of fantastic or hypothetical devices such as perpetual motion machines.
The patent examiners guidelines require that a patent application expresses a specific, credible, and substantial utility. Rejection by an examiner usually requires documentary evidence establishing a prima facie showing that there is no specific, substantial, and credible utility.
Beneficial utility became established as a requirement in United States patent law in 1817 as a result of Lowell v. Lewis (1 Mason. 182; 1 Robb, Pat. Cas. 131 Circuit Court, D. Massachusetts. May Term. 1817.). The utility criterion established by this case is, as Justice Joseph Story wrote in the Court's decision, that, to be patentable, an invention must be "useful" and must "not be frivolous or injurious to the well-being, good policy, or sound morals of society". In spite of this ruling however, patents continued to be granted for devices that could be deemed immoral (e.g. gambling devices, see, e.g., Brewer v. Lichtenstein and Ex parte Murphy) or deceitful (see, Juicy Whip, Inc. v. Orange Bang, Inc. (dealing with a juice dispenser that arguably deceived the public into believing that the liquid seen in the attached reservoir was that which was being dispensed)). In Juicy Whip, the Court of Appeals for the Federal Circuit put an end to the requirement: "Congress never intended that the patent laws should displace the police powers of the States, meaning by that term those powers by which the health, good order, peace and general welfare of the community are promoted…we find no basis in section 101 to hold that inventions can be ruled unpatentable for lack of utility simply because they have the capacity to fool some members of the public."(Juicy Whip Inc. v. Orange Bang Inc., 185 F.3d 1364, 1367–68, 51 USPQ2d 1700, 1702-03 (Fed. Cir. 1999), see also Manual of Patent Examining Procedure 706.03(a)(II))
The last util
The last utility category is practical or specific utility. According to Mueller, "to be patentable an invention must have some real-world use." The utility threshold is relatively easy to satisfy for mechanical, electrical, or novelty inventions, because the purpose of the utility requirement is to ensure that the invention works on some minimal level. However, the practical or specific utility requirement for patentability may be more difficult to satisfy for chemical compound inventions, because of the level of uncertainty when working with these compounds. The United States Supreme Court in Brenner v. Manson held that a novel process for making a known steroid did not satisfy the utility requirement because the patent applicants did not show that the steroid served any practical function. The Court ruled, "... a process patent in the chemical field, which has not been developed and pointed to the degree of specific utility, creates a monopoly of knowledge which should be granted only if clearly commanded by the statute." Practical or specific utility is the requirement for an invention to have a particular purpose.