In the 1942 case of Sola Electric Co. v. Jefferson Electric Co., the United States Supreme Court ruled on a patent dispute between two electric companies. The plaintiff, Sola Electric Company, alleged that Jefferson Electric Company had infringed upon its patent for an electrical transformer design and sought damages as well as an injunction to prevent further infringement. However, the defendant argued that Sola's patent was invalid due to prior art - previous patents or public knowledge which covered similar designs before Sola filed their application. The court found in favor of Jefferson Electric Company, ruling that there was indeed sufficient evidence of prior art which invalidated Sola's claim to originality in their patented design. This decision reinforced the importance of novelty and non-obviousness in granting patents while also highlighting how prior art can be used defensively against claims of infringement.

In the dissenting opinion for the case of Sola Electric Co. v. Jefferson Electric Co., Justice Frank Murphy argued that there was no clear evidence to support a finding of patent infringement by Jefferson Electric Company on Sola's transformer design. He contended that, while both designs served similar functions and had some similarities in appearance, they were not identical nor did they operate identically. Furthermore, he pointed out that many elements of these transformers were common knowledge within the industry at the time and thus could not be considered proprietary inventions belonging solely to Sola Electric Company. Therefore, he disagreed with majority’s decision which held Jefferson liable for patent infringement.