In the case of Champion Spark Plug Co. v. Sanders et al., the U.S Supreme Court dealt with issues related to trademark infringement and unfair competition. The Champion Spark Plug Company, a manufacturer of spark plugs, sued Perfect Reconditioned Spark Plug Co., who were reconditioning used Champion spark plugs and selling them under the original brand name without clearly indicating that they had been reconditioned or refurbished. The court ruled in favor of Champion, stating that such practices constituted trademark infringement as well as unfair competition because it could mislead consumers into believing they were purchasing new products when in fact they were not. This decision reinforced the principle that trademarks are intended to protect both businesses and consumers by ensuring clear identification of product origin.

In the dissenting opinion for Champion Spark Plug Co. v. Sanders, Justice Murphy disagreed with the majority's ruling that reconditioned spark plugs could not be sold under their original brand name without clear indication of their refurbished status. He argued that this decision was based on an overly broad interpretation of trademark infringement and unfair competition laws, which he believed should only apply in cases where there is a likelihood of consumer confusion about the origin or quality of a product. In his view, as long as consumers were aware they were buying reconditioned goods and these goods met certain standards, it did not matter if they bore the original manufacturer's mark; to rule otherwise would unfairly restrict secondary markets and limit consumer choice.