Jack v. Utah Territory was a Supreme Court case from 1876 that dealt with the issue of whether a person of African descent could be convicted of a crime in a Utah court. The case involved a man named Jack, who was accused of stealing a horse in Utah Territory. Jack was convicted and sentenced to two years in prison. The Supreme Court heard the case and ruled in favor of Jack. The Court held that the Utah Territory was part of the United States, and as such, the Fourteenth Amendment applied to the Territory. This Amendment prohibits states from denying any person the equal protection of the laws. The Court held that Jack was denied equal protection of the laws because he was of African descent, and thus his conviction was overturned. The ruling in Jack v. Utah Territory was significant because it was the first time the Supreme Court had applied the Fourteenth Amendment to a territory. This ruling established the precedent that the Fourteenth Amendment applied to all territories of the United States, and that all persons, regardless of race, were entitled to equal protection of the laws.

In the case of Jack v. Utah Territory, Justice Field delivered a dissenting opinion in which he argued that the majority had misinterpreted both state and federal law to reach its conclusion. He noted that under Utah's laws at the time, an Indian could not be convicted of murder unless it was proven beyond a reasonable doubt that they were aware of their actions and intended them to result in death or serious bodily harm. Furthermore, Field argued that Congress had never passed any legislation authorizing such prosecutions against Indians for crimes committed on reservations; thus, he believed this prosecution was unconstitutional as it violated tribal sovereignty rights granted by treaty between tribes and the United States government. Finally, Field concluded by noting his belief that if Congress wanted to authorize such prosecutions then they should pass specific legislation allowing for them rather than relying on general statutes meant for non-Indians living off reservations.