Dant v. District of Columbia was a case heard by the United States Supreme Court in 1875. The case involved a dispute between the District of Columbia and a man named Dant, who had been arrested for failing to pay a fine. Dant argued that the District of Columbia had no authority to arrest him, as the fine was imposed by a court in the District of Columbia, and the District of Columbia had no power to enforce its own laws. The Supreme Court agreed with Dant, ruling that the District of Columbia had no authority to arrest him. The Court held that the District of Columbia was not a state, and therefore did not have the power to enforce its own laws. The Court also held that the District of Columbia was subject to the laws of the United States, and that the United States had the power to enforce its laws in the District of Columbia. The Court's decision in Dant v. District of Columbia was significant, as it established that the District of Columbia was subject to the laws of the United States, and that the United States had the power to enforce its laws in the District of Columbia. This decision has been cited in numerous cases since, and has been used to support the idea that the District of Columbia is subject to the laws of the United States.

In Dant v. District of Columbia, the Supreme Court was asked to decide whether a contract between two parties could be enforced when it had been made in violation of an existing law. The majority opinion held that the contract should not be enforced because it violated public policy and would encourage similar violations in the future. However, Justice Field dissented from this decision, arguing that contracts are generally binding on both parties regardless of any laws or regulations which may have been broken during their formation. He argued that if one party were allowed to break such a contract without consequence then all contracts would become unreliable and therefore unenforceable by either party. Furthermore, he stated that allowing one side to breach a valid agreement while punishing another for doing so would lead to unfairness and injustice within society as well as create confusion over what is legally enforceable under certain circumstances.