Glen v. Fant 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, Glen, was held in a federal prison in the state of Georgia. Glen sought a writ of habeas corpus from the state court, claiming that he was being held in violation of his constitutional rights. 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 remedy, 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 remedy that could only be used to challenge the legality of a person's detention, and not to challenge the conditions of the detention. The Court's decision in Glen v. Fant established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons. The decision also clarified the scope of the writ of habeas corpus, and established that it could only be used to challenge the legality of a person's detention, and not to challenge the conditions of the detention.

Justice Field delivered the dissenting opinion in Glen v. Fant, arguing that the majority's decision was contrary to established precedent and would lead to confusion among lower courts. He argued that a contract between two parties should be interpreted according to its plain language and not by what one party may have intended or expected from it. Furthermore, he noted that if the court were to allow for such interpretation of contracts then there would be no end as each party could claim their own understanding of what they thought had been agreed upon at the time of signing. Justice Field concluded his dissent by stating that while it is important for courts to consider all relevant evidence when interpreting a contract, they must ultimately adhere strictly to its written terms and conditions without regard for any other extraneous factors which might influence their judgment on how those terms should be applied in practice.