McGoon v. Scales 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, William McGoon, was held in a federal prison in the state of Tennessee. McGoon sought a writ of habeas corpus from the state court, claiming that he was being held in violation of the Constitution. The state court granted the writ, and the federal government appealed the decision to the Supreme 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. In conclusion, 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.

In the case of McGoon v. Scales, the Supreme Court was tasked with deciding whether a contract between two parties could be enforced if it had been made in violation of state law. The majority opinion held that such contracts were not enforceable and thus dismissed the plaintiff's claim for damages. However, Justice Field dissented from this decision and argued that while states have authority to regulate certain aspects of contracts, they do not have absolute power over them. He further stated that when a contract is made without violating any public policy or statute, then it should be upheld by courts regardless of its illegality under state law. In conclusion, Justice Field believed that an individual has the right to make their own contractual arrangements as long as those agreements are not contrary to public policy or statutory laws; therefore he would have allowed McGoon's suit against Scales to proceed despite its illegal nature under state law.