In the 1890 case of Sire v. Ellithorpe Air Brake Co., the U.S Supreme Court dealt with a patent dispute. The plaintiff, Sire, alleged that Ellithorpe Air Brake Co had infringed on his patent for an air brake system used in trains. However, the defendant argued that they did not infringe because their product was significantly different from what was described in Sire's patent and thus did not fall under its scope. After examining both systems closely, the court agreed with Ellithorpe's argument and ruled in favor of them stating that there were significant differences between both designs which made them distinct inventions altogether despite serving similar purposes. Therefore, it concluded that no infringement had occurred as claimed by Sire.

The dissenting opinion in the Sire v. Ellithorpe Air Brake Co case argued that the patent granted to Mr. Sire was not for a new invention or discovery, but merely an improvement on existing technology. The justice believed that while improvements can be patented, they must involve more than just substituting one material for another or changing size and form without altering function and principle of operation. In this case, it was contended that Mr. Sire's design simply replaced a lever with a cam - which did not constitute as an inventive step warranting patent protection since both performed similar functions in essentially the same way.