Mattingly v. District of Columbia was a United States Supreme Court case that dealt with the issue of whether a municipality could be held liable for the negligence of its officers. The case arose when a man named Mattingly was injured while working on a bridge in the District of Columbia. He sued the District for damages, claiming that the District was negligent in failing to provide a safe working environment. The Supreme Court held that the District could not be held liable for the negligence of its officers. The Court reasoned that the District was not responsible for the actions of its officers, and that the officers were acting in their official capacity and not as agents of the District. The Court also noted that the District had no control over the officers' actions and could not be held liable for their negligence. The Court's decision in Mattingly v. District of Columbia established that municipalities cannot be held liable for the negligence of their officers. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of municipal liability.

In Mattingly 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 such contracts were not enforceable and should be declared void by the court. However, Justice Field dissented from this ruling on the grounds that while he agreed with the majority's conclusion regarding public policy considerations, he felt that there was no legal basis for declaring such contracts void as a matter of law. He argued that if one party had already performed their obligations under the contract then they should still receive compensation for those services regardless of any violations committed during its formation or execution. Furthermore, Justice Field believed that since both parties had voluntarily entered into an agreement without coercion or fraud being involved then they should both remain bound by its terms unless otherwise provided by statute or other applicable laws governing contractual agreements in general.