United States v. Alire was a United States Supreme Court case that dealt with the issue of whether a Mexican citizen could be convicted of a crime in the United States. The case involved a Mexican citizen, Jose Alire, who was accused of stealing a horse from a United States citizen in California. Alire was arrested and charged with the crime, but he argued that he could not be convicted because he was a Mexican citizen and not a United States citizen. The Supreme Court ultimately ruled in favor of the United States, finding that Alire could be convicted of the crime. The Court reasoned that the United States had jurisdiction over the crime because it had occurred in the United States, and that Alire was subject to the laws of the United States regardless of his citizenship. The Court also noted that the United States had a duty to protect its citizens from crime, and that Alire's citizenship status did not exempt him from the law. The decision in United States v. Alire established that foreign citizens can be held accountable for crimes committed in the United States, regardless of their citizenship status. This ruling has been cited in numerous cases since then, and it remains an important precedent in the area of criminal law.

In United States v. Alire, the Supreme Court was tasked with determining whether a Mexican citizen who had been living in California since before it became part of the United States could be considered an American citizen. The majority opinion held that he could not, as his residence did not confer citizenship upon him and he had never taken any steps to become naturalized. However, Justice Field dissented from this decision and argued that Alire should be recognized as a citizen due to his long-term residency in California prior to its admission into the Union. He noted that Congress has always treated residents of territories acquired by treaty or conquest differently than those residing within states already part of the Union; thus, allowing for special consideration when granting citizenship rights to such individuals based on their length of residence rather than requiring them to go through formal naturalization proceedings like other immigrants would have done at the time.