New Buffalo v. Iron Company was a case heard by the United States Supreme Court in 1881. The case involved a dispute between the New Buffalo Iron Company and the Iron Company of New Buffalo, Michigan. The Iron Company of New Buffalo had been granted a patent for a certain type of iron ore, and the New Buffalo Iron Company had been using the ore without permission. The Iron Company of New Buffalo sued the New Buffalo Iron Company for infringement of their patent. The Supreme Court held that the Iron Company of New Buffalo had a valid patent and that the New Buffalo Iron Company had infringed upon it. The Court also held that the Iron Company of New Buffalo was entitled to damages for the infringement. The Court noted that the patent was valid and that the Iron Company of New Buffalo had a right to protect its patent from infringement. The Court also noted that the New Buffalo Iron Company had acted in bad faith by using the ore without permission. The Court's decision in this case established the principle that patent holders have the right to protect their patents from infringement. This case also established the principle that patent holders are entitled to damages for infringement. This case is still cited today as an example of the importance of protecting intellectual property rights.

In the case of New Buffalo v. Iron Company, Justice Field delivered a dissenting opinion in which he argued that the majority's decision was wrongfully based on an interpretation of state law rather than federal law. He noted that while it is true that states have jurisdiction over certain matters, they do not have exclusive authority to determine questions concerning interstate commerce and contracts between citizens of different states. In this particular case, he believed there were sufficient facts to establish a contract between two parties from different states and thus should be governed by federal laws instead of state laws as determined by the majority opinion. Furthermore, Justice Field argued that even if one accepted the majority’s interpretation of state law as valid, their conclusion still did not follow logically from their reasoning because they failed to consider other relevant factors such as whether or not there had been any consideration given for performance under the alleged contract or if either party had actually received any benefit from its terms. Ultimately, Justice Field concluded his dissent with an assertion that since no court has ever held otherwise on similar cases involving interstate commerce and contracts between citizens residing in different states then this Court should also adhere to those precedents when making its ruling in this matter.