In United States v. Gomez, the Supreme Court of the United States held that a person born in Mexico to Mexican parents was not an American citizen and could be deported from the country without due process. The case arose when Jose Manuel Gomez, who had been living in California since 1852, was arrested by federal authorities for being unlawfully present in the U.S., despite having married an American woman and fathered several children while residing there. In its decision, the court found that under existing law at that time citizenship did not extend to those born outside of America's borders even if their parents were citizens or residents of this country; thus it concluded that Mr. Gomez was subject to deportation proceedings as he lacked any legal right to remain within U.S territory . This ruling has since been overturned by subsequent legislation which now grants automatic citizenship rights based on birthright regardless of where one is born or their parentage status

In United States v. Gomez, the Supreme Court was tasked with determining whether a Mexican citizen who had been living in California since 1853 and had become an American citizen in 1860 could be convicted of treason against the United States for joining a rebellion against it during the Civil War. The majority opinion held that he could not because his allegiance to Mexico ended when he became an American citizen, and thus he did not owe any duty of loyalty or obedience to Mexico at the time of his alleged crime. However, Justice Field dissented from this ruling on two grounds: firstly, that Congress has exclusive authority over naturalization matters; secondly, that even if Gomez's citizenship was valid under state law (which is what the majority opinion assumed), it would still have no effect on his obligations towards Mexico as those were determined by international law rather than domestic laws. He argued further that such obligations do not end simply because one changes their nationality but instead remain until they are released through some formal act or agreement between nations.