Beall v. New Mexico was a case heard by the United States Supreme Court in 1872. The case involved a dispute between the plaintiff, William Beall, and the defendant, the Territory of New Mexico. Beall had been appointed as a justice of the peace in the Territory of New Mexico in 1867. However, in 1869, the Territorial Legislature passed a law that abolished the office of justice of the peace and replaced it with the office of justice of the district court. Beall argued that this law was unconstitutional because it deprived him of his office without due process of law. The Supreme Court agreed with Beall and held that the Territorial Legislature had violated the Constitution by depriving him of his office without due process of law. The Court held that the Territorial Legislature had violated the Fourteenth Amendment, which guarantees that no state shall “deprive any person of life, liberty, or property, without due process of law.” The Court also held that the Territorial Legislature had violated the Fifth Amendment, which guarantees that no person shall be “deprived of life, liberty, or property, without due process of law.” The Court held that Beall was entitled to compensation for the loss of his office and ordered the Territorial Legislature to pay him the amount of his salary for the period of time he had served as justice of the peace. The Court also held that the Territorial Legislature was not allowed to pass any laws that would deprive any person of their office without due process of law. This case established an important precedent that has been used in many subsequent cases involving the deprivation of office without due process of law.

In Beall v. New Mexico, the Supreme Court was asked to decide whether a state could tax property owned by an individual who had been granted land in exchange for military service. The majority opinion held that states have the right to impose taxes on such property, but Justice Field dissented from this ruling. He argued that Congress has exclusive power over federal lands and any taxation of them must be done with its consent; since no such consent had been given in this case, he believed it would be unconstitutional for New Mexico to levy a tax on the plaintiff's land grant. Furthermore, Field noted that if states were allowed to impose taxes without Congressional approval then they would effectively have control over all federal lands within their borders - something which is not provided for under the Constitution or any other law. As such, he concluded that allowing New Mexico's taxation of these properties would violate both constitutional principles and congressional authority over public lands