Express Company v. Railroad Company was a case heard by the United States Supreme Court in 1878. The case involved a dispute between the Express Company and the Railroad Company over the terms of a contract. The Express Company had contracted with the Railroad Company to transport goods from one place to another. The Railroad Company had agreed to transport the goods at a certain rate, but then later increased the rate without the Express Company's consent. The Express Company argued that the Railroad Company had breached the contract by increasing the rate without their consent. The Supreme Court held that the Railroad Company had breached the contract by increasing the rate without the Express Company's consent. The Court found that the Railroad Company had violated the terms of the contract and was liable for damages. The Court also held that the Express Company was entitled to recover the difference between the rate that was agreed upon and the rate that was actually charged. The Court's decision in this case established that a party to a contract cannot unilaterally change the terms of the contract without the consent of the other party. This decision has been cited in numerous cases since then and is still an important part of contract law today.

Justice Field delivered the dissenting opinion in Express Company v. Railroad Company, arguing that the majority's decision was contrary to both law and justice. He argued that it was a fundamental principle of common law that when an express company is employed by a railroad company to carry out its business, they are liable for any damage caused by their negligence or misconduct while doing so. In this case, he argued, there had been no evidence presented which showed that either party had acted negligently or wrongfully; instead, the only issue before them was whether one party should be held responsible for damages incurred due to another's negligence. As such, Justice Field concluded that neither party could be held liable and thus affirmed his dissent from the majority opinion.