In the United States v. Nix case of 1902, the Supreme Court was tasked with determining whether tomatoes should be classified as fruits or vegetables under customs regulations. The dispute arose when John Nix's company, a produce importer, was charged duties on their imported tomatoes by Edward L. Hedden, Collector of the Port of New York who argued that they were vegetables and thus taxable under Tariff Act provisions for "vegetables in their natural state." However, Nix contended that botanically speaking, tomatoes are indeed fruits and therefore not subject to these tariffs. The court unanimously ruled in favor of Hedden stating that while botanically a tomato is technically a fruit; however for purposes related to trade and commerce (and within common language), it is more often treated as a vegetable which falls under tariff laws at the time.

In the dissenting opinion for United States v. Nix, Justice Harlan argued that the majority's decision to allow a patent on a hybrid plant was incorrect and would have far-reaching implications. He believed that nature, not man, had created this new type of plant through cross-pollination and therefore it could not be patented under U.S law which only allowed patents for inventions or discoveries by humans. Harlan warned that allowing such patents would open up all natural phenomena to potential patent claims, stifling scientific research and development as researchers might fear legal repercussions from studying or experimenting with naturally occurring organisms or elements. Furthermore, he expressed concern about the potential monopolization of resources if companies were able to claim exclusive rights over certain plants or animals simply because they happened upon them first.