Armstrong's Foundry was a case heard by the United States Supreme Court in 1867. The case involved a dispute between the owner of a foundry and the workers who had been employed there. The owner had refused to pay the workers for their labor, claiming that the work was done without a contract and that the workers had not been paid in accordance with the terms of the contract. The workers argued that they had been promised a certain amount of money for their labor and that the owner had failed to pay them. The Supreme Court ruled in favor of the workers, finding that the owner had breached the contract and was liable for the wages due to the workers. The Court held that the owner was obligated to pay the workers the wages they were promised, regardless of whether or not a contract had been signed. The Court also held that the owner was liable for any damages caused by his breach of the contract. This ruling established the principle that employers must pay their employees for their labor, regardless of whether or not a contract has been signed.

In Armstrong's Foundry, the Supreme Court was asked to decide whether a contract between two parties for the sale of goods could be enforced if it had been made without consideration. The majority opinion held that such contracts were not enforceable because they lacked consideration. However, in his dissent Justice Field argued that when two parties enter into an agreement with mutual promises and obligations, there is sufficient consideration to make the contract binding even if no money or other valuable thing has changed hands. He further argued that this rule should apply regardless of whether one party stands to benefit more than another from their agreement as long as both sides have received something in return for their promise. Furthermore, he stated that allowing such agreements would promote fairness and justice by preventing either side from taking advantage of the other after a deal has already been struck but before any payment has been made.