De Witt v. Berry was a Supreme Court case that was decided in 1845. The case involved a dispute between two parties over a contract for the sale of land. The plaintiff, De Witt, had entered into a contract with the defendant, Berry, to purchase a tract of land in the state of New York. The contract specified that the purchase price was to be paid in installments over a period of time. De Witt had made all of the payments as required by the contract, but Berry refused to convey the land to him. De Witt then brought suit against Berry, claiming that he had fulfilled all of the terms of the contract and was entitled to the land. The Supreme Court agreed with De Witt and held that Berry was obligated to convey the land to him. The Court held that the contract was valid and enforceable, and that Berry had breached it by refusing to convey the land. The Court also held that De Witt was entitled to damages for the breach of contract. This case established the principle that contracts are binding and enforceable, and that parties who breach them are liable for damages.

In the Supreme Court case of De Witt v. Berry, Justice Harlan delivered a dissenting opinion in which he argued that the majority had incorrectly interpreted the Fourteenth Amendment's Equal Protection Clause. He stated that while it was true that all citizens are equal under the law, this did not mean they were entitled to absolute equality in every respect; rather, states have broad discretion when it comes to making laws and regulations concerning their own internal affairs. In this particular case, Justice Harlan felt that Mississippi had acted within its rights by enacting a statute requiring African Americans who wished to vote or hold public office to take an additional literacy test beyond what white citizens were required to do. As such, he concluded that there was no violation of constitutional rights and thus no grounds for overturning Mississippi's law on appeal.