Weightman v. Clark was a United States Supreme Court case that dealt with the issue of whether a state court had the authority to issue a writ of habeas corpus to a prisoner who was being held in a federal prison. The case arose when a prisoner, William Weightman, was held in a federal prison in the District of Columbia. Weightman sought a writ of habeas corpus from the Supreme Court of the District of Columbia, which was denied. Weightman then appealed to the Supreme Court of the United States. The Supreme Court held that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in a federal prison. The Court reasoned that the power to issue a writ of habeas corpus was a power reserved to the federal government, and that the state court did not have the authority to interfere with the federal government's power. The Court also noted that the writ of habeas corpus was a fundamental right, and that the state court should not be allowed to interfere with the federal government's power to protect this right. The Court's decision in Weightman v. Clark established that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in a federal prison. This decision has been cited in numerous cases since then, and has been used to support the idea that the federal government has the exclusive power to issue writs of habeas corpus.

In Weightman v. Clark, the United States Supreme Court was tasked with determining whether a contract between two parties could be enforced even though it had been made without consideration. The majority opinion held that the contract was not enforceable because there was no consideration given for its formation. Justice Field dissented from this decision and argued that contracts should be enforced if they are fair and equitable to both parties regardless of whether or not consideration is present. He reasoned that courts should look at all relevant facts in order to determine if a contract is justifiable, including any promises made by either party prior to entering into an agreement as well as any subsequent actions taken in reliance on those promises. Furthermore, he argued that when one party has already acted upon their promise then it would be unjust for them to suffer loss due to lack of consideration since they have already performed their part of the bargain and thus deserve protection under law.