Tillson v. United States was a Supreme Court case decided in 1894. The case involved a dispute between the United States and the heirs of a deceased soldier, William Tillson, over the ownership of a tract of land in the state of Washington. Tillson had been granted the land by the United States in 1871, but had died before he was able to take possession of it. His heirs argued that they were entitled to the land, while the United States argued that the land had reverted to the government upon Tillson's death. The Supreme Court ultimately sided with the United States, ruling that the land had reverted to the government upon Tillson's death. The Court held that the United States had a right to the land, as it had been granted to Tillson by the government and he had not taken possession of it before his death. The Court also held that the heirs had no right to the land, as they had not taken any steps to claim it before Tillson's death. The Court's decision was based on the principle that the United States had a right to the land, as it had been granted to Tillson by the government and he had not taken possession of it before his death.

In the Supreme Court case of Tillson v. United States, Justice Black delivered a dissenting opinion. He argued that the majority’s decision to uphold a conviction for failing to register as an alien was wrong because it violated due process and equal protection under the law. The Alien Registration Act required aliens who had been in the country for more than six months to register with local authorities or face criminal penalties; however, this requirement did not apply equally across all states since some states had their own registration laws which were stricter than federal requirements. As such, Justice Black argued that this unequal application of the law constituted a violation of due process and equal protection rights guaranteed by both state and federal constitutions. Furthermore, he noted that there was no evidence presented at trial showing any harm caused by Tillson's failure to register as an alien; thus, his conviction should be overturned on these grounds alone.