Farmers' Loan and Trust Company v. Newman was a United States Supreme Court case that dealt with the issue of whether a state court could enjoin a federal court from hearing a case. The case arose when the Farmers' Loan and Trust Company sought to enjoin the Newman brothers from collecting a debt from the company. The Newmans argued that the state court lacked jurisdiction to enjoin the federal court from hearing the case. The Supreme Court held that the state court did not have the power to enjoin the federal court from hearing the case. The Court reasoned that the state court lacked the power to interfere with the federal court's jurisdiction. The Court further held that the state court could not interfere with the federal court's jurisdiction by enjoining the federal court from hearing the case. The Court's decision in this case established the principle that state courts cannot interfere with the jurisdiction of federal courts. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of federal court jurisdiction.

In Farmers' Loan and Trust Company v. Newman, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a non-resident against a resident of that state. The majority opinion held that the state court did have such jurisdiction, but Justice Field dissented from this decision. He argued that under the Constitution's full faith and credit clause, states are required to give effect to judgments rendered in other states; thus, if another court has already heard an action between two parties who were both residents of its own state at the time it was filed, then no other court should be allowed to hear it again unless there is some special reason for doing so. Furthermore, he argued that allowing multiple courts with concurrent jurisdiction would lead to confusion and uncertainty as well as create opportunities for fraud or collusion among litigants seeking favorable rulings from different courts on identical issues.