Ely-Norris Safe Co. (Ely) (plaintiff) manufactured metal safes. It was known for its unique design involving a hidden “explosion chamber” to prevent burglary of the safe. No other company manufactured such a design. As the design gained popularity, Mosler Safe Co. (Mosler) (defendant) began manufacturing similar safes. However, Mosler’s safes included a metal band around which the explosion chamber would be in one of Ely’s safes. Mosler deceived its customers by falsely telling them the band covered an explosion chamber when it did not. Ely brought suit against Mosler seeking an injunction preventing the sale of safes with metal bands, and from representing that any of Mosler’s safes contained an explosion chamber. At trial, evidence was introduced showing that all Mosler’s safes bore its own name and address, and that Mosler never gave its customers reason to believe the safes it sold were manufactured by Ely. The trial court denied Ely’s request for an injunction against Mosler, and Ely appealed. The United States Supreme Court granted certiorari, and reversed the lower court’s decision to deny Ely’s request for an injunction against Mosler. Mosler appealed.