Ex Parte Phenix Insurance Company & Others is a United States Supreme Court case that dealt with the issue of whether a state court had the authority to issue an injunction against a foreign corporation. The case arose when the Phenix Insurance Company, a foreign corporation, was sued in a state court in Alabama. The state court issued an injunction against the company, prohibiting it from doing business in the state. The company appealed the decision to the Supreme Court, arguing that the state court did not have the authority to issue an injunction against a foreign corporation. The Supreme Court held that the state court did not have the authority to issue an injunction against a foreign corporation. The Court reasoned that the state court lacked jurisdiction over the foreign corporation, and that the injunction was therefore invalid. The Court also noted that the state court had not provided the company with due process of law, as required by the Fourteenth Amendment. The Court's decision in this case established that state courts do not have the authority to issue injunctions against foreign corporations. This decision has been cited in numerous subsequent cases, and has been used to support the principle that foreign corporations are not subject to the jurisdiction of state courts.

In Ex Parte Phenix Insurance Company & Others, the Supreme Court was asked to decide whether a state court had jurisdiction over an insurance company incorporated in another state. The majority opinion held that it did not have such jurisdiction, as the Constitution of the United States grants exclusive authority to Congress to regulate interstate commerce and thus prohibits states from exercising any control over companies engaged in such commerce. Justice Field dissented from this decision, arguing that while Congress has been granted broad powers under the Commerce Clause of the Constitution, those powers do not extend so far as to prohibit states from exercising their own police power when regulating corporations within their borders. He argued further that if a corporation is doing business within a particular state then it should be subject to its laws and regulations just like any other entity operating there. In conclusion, he asserted that since Phenix Insurance Company was conducting business in Louisiana at the time of suit being brought against them by citizens of Louisiana they were properly subject to its courts’ jurisdiction regardless of where they were incorporated or chartered.