The U.S. Supreme Court case Saxlehner v. Nielsen in 1900 revolved around trademark infringement and unfair competition. Andreas Saxlehner, the owner of a Hungarian mineral water business, sued Hans Peter Nielsen for selling an imitation product under his brand name "Hunyadi Janos". The lower court ruled in favor of Saxlehner, stating that Nielsen's actions constituted as both trademark infringement and unfair competition due to the deceptive similarity between the two products' labels. However, on appeal to the Supreme Court, it was held that while there was indeed an act of unfair competition by Nielsen through misrepresentation causing confusion among consumers about which product they were purchasing; this did not constitute a violation of federal trademark law because 'Hunyadi Janos' had become a generic term for laxative mineral water rather than being associated with any specific source or producer.

In the dissenting opinion for SAXLEHNER v. NIELSEN, 1900, it was argued that the majority's decision to deny Saxlehner relief on his trademark infringement claim was incorrect. The dissenting justices believed that Nielsen and other defendants had intentionally deceived consumers by selling a product under Saxlehner's well-known brand name "Hunyadi Janos". They pointed out that this deception caused significant harm to Saxlehner’s business reputation and profits. Furthermore, they disagreed with the majority's interpretation of existing case law regarding trademarks and unfair competition. In their view, previous cases supported granting relief in situations like this where there is clear evidence of intentional deception causing harm to another party’s business interests.