In the 1893 case of North Chicago Rolling Mill Company v. St. Louis Ore and Steel Company, the U.S Supreme Court was tasked with determining whether a patent for an improved method of manufacturing iron and steel rails was valid or not. The North Chicago Rolling Mill Co., who held the patent, claimed that their process resulted in superior quality rails which were less likely to crack under pressure compared to traditional methods. However, St. Louis Ore & Steel Co argued that this patented process did not involve any new invention but merely used known principles in a more efficient manner. The court ruled in favor of St.Louis Ore & Steel Co., stating that while it is true that using known principles more efficiently can result in better products, such improvements do not qualify as inventions eligible for patents under U.S law unless they introduce some novel concept or method into the production process.

The dissenting opinion in the case of North Chicago Rolling Mill Company v. St. Louis Ore and Steel Company argued that the majority's decision was based on an incorrect interpretation of patent law, specifically regarding what constitutes a new invention or discovery. The dissent pointed out that even small changes to existing technology can be considered inventions if they result in significant improvements or efficiencies, as was the case with the rolling mill process at issue in this case. They contended that these improvements were not merely obvious modifications but represented a novel application of mechanical principles which deserved patent protection under U.S law.