Carter v. Greenhow 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 person who was being held in custody by a federal court. The case arose when a man named William Greenhow was arrested by federal authorities in Virginia for alleged violations of the Neutrality Act. Greenhow was held in federal custody, but his family sought a writ of habeas corpus from the state court in order to have him released. The state court granted the writ, but the federal court refused to comply. The Supreme Court ultimately held that the state court did not have the authority to issue the writ of habeas corpus. The Court reasoned that the writ of habeas corpus was a federal power, and that the state court did not have the authority to interfere with the federal court's decision to hold Greenhow in custody. The Court also noted that the writ of habeas corpus was a fundamental right, and that the federal government had the power to protect its citizens from unlawful detention. In conclusion, the Supreme Court held that the state court did not have the authority to issue a writ of habeas corpus to a person who was being held in custody by a federal court. The Court reasoned that the writ of habeas corpus was a federal power, and that the state court did not have the authority to interfere with the federal court's decision to hold Greenhow in custody.

Justice Field delivered the dissenting opinion in Carter v. Greenhow, arguing that the majority's decision was a misinterpretation of Virginia law and an infringement on states' rights. He argued that under Virginia law, if a debtor failed to pay their debt within one year after it became due, then any security given for such debt would become voidable at the option of the creditor. In this case, he argued that since more than one year had passed between when Greenhow gave his note as security and when Carter sued him for nonpayment of said note, then Greenhow should have been allowed to plead his right to avoid liability on account of lapse in time. Furthermore, Justice Field contended that by denying this plea from being heard in court based solely upon its form rather than its substance violated both state laws and principles established by prior Supreme Court decisions which held that federal courts must respect state laws unless they are clearly unconstitutional or repugnant to federal statutes or treaties.