In the case of Diamond, Commissioner of Patents and Trademarks v. Bradley et al., 1980, the U.S Supreme Court ruled on whether a computer program could be patented under U.S law. The court held that an invention must either improve or change the functioning of a machine to be patentable and that abstract ideas are not eligible for patents. In this case, Freeman J. Bradley had developed an algorithm used in oil exploration but did not claim any new machinery or physical process related to it; he only claimed his mathematical formula's application in programming a digital computer to perform certain functions during drilling exploratory boreholes. The court found that while his method was innovative and useful within its industry, it was essentially just manipulating abstract mathematical principles without producing any tangible innovation in technology or process - thus falling outside patent eligibility as per Section 101 of Patent Act.

In the dissenting opinion for Diamond, Commissioner of Patents and Trademarks v. Bradley et al., Justice William Rehnquist argued that the majority's decision to allow a patent on an invention involving computer software was misguided. He contended that allowing patents on abstract ideas or mathematical formulas would stifle innovation rather than promote it, as intended by patent law. Furthermore, he expressed concern about the potential for monopolization in this rapidly developing field if such broad patents were allowed. He also disagreed with the majority's interpretation of legislative history regarding Congress' intent when they revised patent laws in 1952, believing there was no clear indication that they intended to include software within its scope.