Mansfield v. Excelsior Refining Company was a Supreme Court case decided in 1891. The case involved a dispute between the plaintiff, Mansfield, and the defendant, Excelsior Refining Company, over a contract for the sale of oil. Mansfield had contracted to sell oil to Excelsior, but Excelsior refused to pay the agreed-upon price. Mansfield then sued Excelsior for breach of contract. The Supreme Court held that Excelsior was liable for breach of contract. The Court found that the contract between the parties was valid and enforceable, and that Excelsior had breached its obligations under the contract by refusing to pay the agreed-upon price. The Court also held that Mansfield was entitled to damages for the breach of contract. The Court's decision in Mansfield v. Excelsior Refining Company established the principle that parties to a contract are legally bound to fulfill their obligations under the contract. The decision also established that a party who breaches a contract is liable for damages. This case is still cited today as an important precedent in contract law.

In the case of Mansfield v. Excelsior Refining Company, Justice Harlan delivered a dissenting opinion in which he argued that the majority had failed to consider all relevant facts and evidence when ruling on the case. He believed that there was sufficient evidence presented by both parties to support their respective positions and thus it should not have been decided so quickly without further consideration. Furthermore, he argued that if the court had taken into account certain factors such as whether or not an agreement existed between Mansfield and Excelsior prior to his injury, then they may have come to a different conclusion than what was ultimately reached. In sum, Justice Harlan felt strongly that more time should have been spent considering all aspects of this particular dispute before making any final decisions regarding liability for damages suffered by Mansfield due to his workplace accident with Excelsior's machinery.