Blanchard v. Putnam 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 held in a federal prison. The case arose when a prisoner, Blanchard, was held in a federal prison in Massachusetts. Blanchard sought a writ of habeas corpus from the state court, which was denied by the federal court. 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 writ of habeas corpus was a federal prerogative and that the state court did not have the authority to interfere with the federal government's power to imprison individuals. 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 imprison individuals. The Court concluded that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in a federal prison.

In Blanchard v. Putnam, the Supreme Court was tasked with determining whether a contract between two parties could be enforced if it had been made in violation of an existing state law. The majority opinion held that such contracts were not enforceable and therefore the plaintiff's claim should be dismissed. However, Justice Field dissented from this decision and argued that while it is true that a contract cannot violate public policy or any positive law of the state, there are instances where enforcing such contracts would still be beneficial to society as a whole. He further argued that when both parties have acted in good faith and without knowledge of any legal impediment to their agreement then they should not suffer for their ignorance; instead, courts should strive to uphold these agreements whenever possible so as to promote fairness and justice within society.