In the case of Hart Steel Company et al. v. Railroad Supply Company in 1916, the U.S Supreme Court was tasked with determining whether a patent for an invention could be invalidated due to prior use by another party who had not patented it. The dispute arose when Hart Steel Company sued Railroad Supply Company for infringing on their patent concerning a certain type of railway switch stand. However, Railroad Supply argued that they were using this technology before Hart Steel obtained its patent and therefore did not violate any rights. The court ruled in favor of Hart Steel stating that even if someone else used the invention earlier, if they didn't apply for a patent within two years from its first public use or sale, then anyone can legally obtain a valid patent over it later on. This ruling established an important precedent regarding "prior user rights" under US Patent Law.

In the dissenting opinion for Hart Steel Company et al. v. Railroad Supply Company, it was argued that the majority's decision to uphold a lower court ruling in favor of Railroad Supply Co., which had sued Hart Steel over patent infringement, was incorrect. The dissenting justices believed that the patent at issue should not have been granted in the first place because it did not meet necessary criteria for novelty and non-obviousness - key requirements for obtaining a patent under U.S law. They contended that there were prior existing technologies similar to what was claimed as new by Railroad Supply Co., thus making their claim unpatentable due to lack of originality or innovation. Furthermore, they disagreed with how evidence presented during trial proceedings had been interpreted by both lower courts and their fellow Supreme Court justices, arguing instead that this evidence supported Hart Steel's defense against allegations of infringement.