In Higueras v. United States, the Supreme Court ruled that a treaty between Mexico and the United States did not grant citizenship to Mexicans living in California at the time of its ratification. The plaintiff argued that he was entitled to naturalization under Article 8 of the Treaty of Guadalupe Hidalgo, which provided for Mexican citizens residing in territories ceded by Mexico to become U.S. citizens upon taking an oath of allegiance and registering with local authorities within one year after ratification. However, Chief Justice Salmon P Chase held that this provision only applied prospectively; it could not be used retroactively to confer rights on those who were already present when it was ratified. Thus, despite being born in California before statehood and having resided there since birth, Higueras' claim for citizenship failed because he had not taken advantage of his opportunity during the specified period following ratification as required by law

In Higueras v. United States, the Supreme Court ruled that a Mexican citizen who had been living in California since 1846 was not eligible for naturalization because he did not meet the residency requirements of five years prior to filing his application. The dissenting opinion argued that Congress had never intended to exclude Mexicans from becoming citizens and that it would be unjust to deny them citizenship based on their race or national origin. Furthermore, they argued that if Congress wanted to limit naturalization rights only to those who were present in the country at its formation then it should have made this clear when passing laws related to immigration and naturalization. They concluded by saying that denying someone's right of citizenship due solely on their nationality violated both justice and equity as well as being contrary to public policy.