In the United States v. Hammers case of 1910, the Supreme Court dealt with a dispute over land ownership in Oklahoma. The plaintiff, the U.S government, claimed that defendant William Hammers had unlawfully taken possession of and made improvements on a piece of public land before it was officially opened for settlement under federal law. The lower court ruled in favor of Hammers based on his "color of title" claim - he believed he had legal right to the property due to an erroneous government survey which marked it as part of his adjacent plot. However, upon appeal by the U.S., this decision was reversed by Justice Day who stated that color-of-title defense could not be used when dealing with public lands since they are governed by specific laws and regulations meant to ensure fair distribution among settlers. Therefore, any prior occupation or improvement done without official sanction is considered illegal encroachment.

In the dissenting opinion for United States v. Hammers, 1910, the justice disagreed with the majority's decision to uphold Hammers' conviction for mail fraud. The dissent argued that while Hammers may have acted dishonestly in his business dealings, he did not technically violate any federal laws related to mail fraud because he did not use the postal service as a means of executing his fraudulent scheme. Instead, it was incidental to his actions and therefore should not fall under federal jurisdiction. Furthermore, they believed that this case represented an overreach of federal power into areas traditionally governed by state law such as contract disputes and property rights. They feared that upholding this conviction would set a dangerous precedent allowing for increased federal intervention in private affairs.