Transportation Line v. Hope was a United States Supreme Court case that addressed the issue of whether a contract between two parties was valid. The case involved a contract between the Transportation Line and Hope, a steamship company. The contract stated that the Transportation Line would provide steamship services to Hope for a certain period of time. However, Hope failed to pay the agreed-upon amount for the services, and the Transportation Line sued for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was clear and unambiguous, and that the parties had agreed to the terms of the contract. The Court also noted that Hope had accepted the services provided by the Transportation Line and had failed to pay the agreed-upon amount. Therefore, the Court held that the contract was valid and enforceable, and that the Transportation Line was entitled to damages for breach of contract.

In Transportation Line v. Hope, the Supreme Court was asked to decide whether a contract between two parties that had been partially performed could be enforced by one of them against the other. The majority held that it could not because there was no consideration for such an agreement and thus it lacked mutuality of obligation. Justice Field dissented from this opinion, arguing that when part performance has occurred on both sides of a contract, then each party should be bound by its terms regardless of any lack of consideration or mutuality in the original agreement. He argued further that if partial performance is sufficient to create an enforceable contract then courts should not look into questions about why those performances were made; rather they should simply recognize their existence as evidence enough to support enforcement under equitable principles even if there is no legal basis for doing so.