Ex parte Clodomiro Cota was a United States Supreme Court case that dealt with the issue of whether a Mexican citizen who had been living in the United States for many years was entitled to the protection of the United States Constitution. The case arose when Clodomiro Cota, a Mexican citizen, was arrested in Arizona for the crime of vagrancy. Cota argued that he was entitled to the protection of the United States Constitution, as he had been living in the United States for many years and had become a de facto citizen. The Supreme Court held that Cota was not entitled to the protection of the United States Constitution, as he was not a citizen of the United States. The Court reasoned that the Constitution only applies to citizens of the United States, and that Cota was not a citizen because he had not been naturalized. The Court also noted that Cota had not taken any steps to become a citizen, such as filing a petition for naturalization. The Court's decision in Ex parte Clodomiro Cota established that non-citizens living in the United States are not entitled to the same constitutional protections as citizens. This decision has been cited in numerous subsequent cases dealing with the rights of non-citizens.

In Ex Parte Clodomiro Cota, the Supreme Court was asked to decide whether a Mexican citizen who had been living in Arizona for over twenty years could be deported. The majority opinion held that he could not be deported because he had established residency and his rights were protected by the Treaty of Guadalupe Hidalgo. However, Justice Field dissented from this decision on the grounds that Congress has exclusive power to determine immigration policy and deport aliens as it sees fit. He argued that treaties do not override congressional authority in such matters, nor can they create any right or privilege which would otherwise be denied under federal law. Furthermore, Field noted that even if Cota did have some sort of legal status due to his long-term residence in Arizona, deportation proceedings should still take place so as to ensure proper enforcement of immigration laws throughout the country.