In the case of Mosler Safe Company v. Ely-Norris Safe Company, 1926, the U.S Supreme Court ruled in favor of Mosler Safe Co., overturning a previous decision by the lower court that had found them guilty of patent infringement. The dispute centered around a specific type of safe design patented by Ely-Norris which included an "explosive chamber" as an anti-burglary device. The lower court had held that Mosler's safes infringed upon this patent due to their use of similar technology. However, on appeal to the Supreme Court, it was determined that while both designs utilized explosive chambers for security purposes, they functioned in fundamentally different ways and thus did not constitute infringement under existing patent law.

In the dissenting opinion for Mosler Safe Company v. Ely-Norris Safe Company, it was argued that the majority's decision to uphold a patent infringement claim against Mosler was incorrect due to an improper interpretation of what constitutes "equivalent" in terms of patent law. The dissenting justices believed that while there were similarities between the safes produced by both companies, they were not identical or equivalent as defined by existing patent laws. They contended that minor alterations and improvements made by Mosler did not constitute infringement on Ely-Norris' patents because these changes resulted in a product with different characteristics and improved functionality. Therefore, they disagreed with the majority's ruling which found Mosler guilty of infringing upon Ely-Norris’ patents.