Jose Maria Fuentes v. The United States was a case heard by the Supreme Court in 1859 that dealt with the issue of slavery and freedom. At its core, it asked whether an individual born into slavery could be considered free if they were taken to a state or territory where slavery had been abolished. In this particular case, Jose Maria Fuentes had been born into slavery but later taken to California which had outlawed the practice of owning slaves at that time. He argued that he should therefore be considered free under California law and not subject to being returned as property back to his former owner in Louisiana who still held him as such according to their laws on slave ownership. After hearing arguments from both sides, the Supreme Court ultimately ruled against Fuentes stating that since Congress did not have any authority over states' rights regarding matters like this one involving personal liberty, then each state would need to decide for itself how it wished handle cases like these concerning individuals brought within its borders from other places where different laws applied pertaining specifically to them due solely based on their status as either slave or free person before entering said jurisdiction's boundaries.

In the case of Jose Maria Fuentes v. The United States, Justice McLean delivered a dissenting opinion in which he argued that the court should have considered whether or not Fuentes was an inhabitant of California at the time it became part of the United States. He believed that if this had been taken into account, then Fuentes would be entitled to pre-emption rights under existing law and thus allowed to purchase land from public lands without paying for it. In his view, Congress had intended for such individuals to receive these rights when they were living on public lands prior to their becoming part of the Union. Furthermore, he argued that since there was no evidence presented by either party as to whether or not Fuentes met this criteria, then summary judgment should not have been granted against him and instead a trial should have occurred so all facts could be heard before any decision was made regarding his claim.