In the case of Stelos Co. v. Hosiery Motor-Mend Corp., the Supreme Court examined a dispute over patent infringement in 1934. The plaintiff, Stelos Company, held a patent for an invention that repaired runs and snags in hosiery using heat generated by electricity to fuse threads together without any visible seams or knots. They accused Hosiery Motor-Mend Corporation of infringing on this patent with their own similar device used for mending stockings and socks. The lower courts had ruled in favor of the defendant, finding no evidence of infringement as there were significant differences between both devices' design and operation method despite serving similar functions. Upon reaching the Supreme Court, it was determined that while two inventions may serve identical purposes or achieve similar results, they are not necessarily equivalent if they employ different means or methods to do so. Therefore, even though both devices served to repair hosiery using heat from electric current - one did so through direct application while another utilized indirect heating via conduction - these operational differences were deemed substantial enough to rule out any claims of equivalence under patent law. As such, the court upheld previous rulings stating that Hosiery Motor-Mend Corporation's product did not infringe upon Stelos Company's patented invention.

The dissenting opinion in the case of Stelos Co. v. Hosiery Motor-Mend Corp., 1934, argued that the majority's decision to uphold a lower court ruling against Stelos Company was incorrect because it failed to properly consider the nature and purpose of patent law. The dissent contended that patents are intended not just as rewards for inventors but also as incentives for innovation and progress in technology and industry. By upholding a ruling that effectively invalidated Stelos' patent on its hosiery mending machine, they believed the Court had undermined this fundamental principle of patent law by discouraging future invention and development rather than encouraging it. Furthermore, they disagreed with the majority's interpretation of what constitutes 'prior art', arguing that earlier designs cited by Hosiery Motor-Mend were not sufficiently similar or relevant to be considered prior art capable of invalidating Stelos' patent.