Smith v. Adsit is a United States Supreme Court case that was decided in 1875. The case involved a dispute between two parties over a contract for the sale of a horse. The plaintiff, Smith, had agreed to purchase a horse from the defendant, Adsit, for $100. Smith paid Adsit $50 as a down payment and Adsit delivered the horse to Smith. Smith then refused to pay the remaining $50, claiming that the horse was not of the quality that Adsit had promised. The Supreme Court held that Smith was not entitled to a refund of the $50 down payment. The Court reasoned that Smith had accepted the horse and had not returned it to Adsit, so Adsit was entitled to keep the $50. The Court also held that Smith was not entitled to damages for the difference between the value of the horse and the price he had agreed to pay. The Court reasoned that Smith had accepted the horse and had not returned it, so Adsit was entitled to keep the $50. The Court's decision in Smith v. Adsit established that a buyer who accepts a product and does not return it is not entitled to a refund or damages for the difference between the value of the product and the price paid. This decision has been cited in numerous subsequent cases involving disputes over the sale of goods.

Justice Field delivered the dissenting opinion in Smith v. Adsit, arguing that the majority had erred in its interpretation of a contract between two parties. He argued that under New York law, which was applicable to this case, it was clear that when one party agreed to pay another for services rendered and accepted those services without any objection or reservation as to their quality or quantity, then an implied promise arose from such acceptance whereby payment would be made according to the terms of the agreement. In this instance he believed there were sufficient facts presented by Smith's complaint indicating she had performed her part of the bargain and should have been allowed relief on her claim against Adsit for breach of contract. Justice Field concluded his dissent by noting that if courts did not enforce contracts fairly and equitably then they could not expect citizens to abide by them nor respect judicial decisions based upon them.