Ex Parte Gordon was a United States Supreme Court case in which the court held that an individual could not be convicted of larceny for taking property from another person without their consent if they believed, even mistakenly, that they had a right to take it. The defendant in this case, John Gordon, had taken some horses and mules from his former employer's farm believing them to be his own. He argued that he should not have been convicted of larceny because he honestly thought the animals were rightfully his due to an oral agreement between himself and the owner. The Supreme Court agreed with him and reversed the conviction on appeal. This decision established precedent for future cases involving similar circumstances; individuals cannot be found guilty of theft or larceny if they can demonstrate good faith belief in their legal entitlement to take possession of someone else’s property.

In Ex Parte Gordon, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving an alleged breach of contract between two citizens of different states. The majority opinion held that the state court did not have jurisdiction in this matter because it involved interstate commerce and thus fell under federal authority. However, Justice Field dissented from this decision on the grounds that Congress had not yet passed any laws regulating interstate commerce and therefore there was no basis for denying the state court's jurisdiction. He argued further that if Congress wanted to regulate such matters they should do so explicitly rather than relying on judicial interpretation of existing law. In conclusion, Justice Field believed that since Congress had not taken action in this area then it would be wrong for the Court to deny a state its right to exercise its own powers within its own borders.