Evans v. Patterson was a United States Supreme Court case that was decided in 1866. The case involved a dispute between two parties over a contract for the sale of a slave. The plaintiff, Evans, had entered into a contract with the defendant, Patterson, to purchase a slave for $1,000. Evans paid the full amount, but Patterson refused to deliver the slave. Evans then sued Patterson for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the sale of slaves was legal in the state where the contract was made, and that the contract was not contrary to public policy. The Court also held that the contract was not voidable due to the fact that the slave was not delivered. The Court held that Patterson was liable for breach of contract and ordered him to pay damages to Evans. The decision in Evans v. Patterson was significant because it established that contracts for the sale of slaves were valid and enforceable. This decision was important in the context of the Civil War, as it provided legal protection for those who had entered into contracts for the sale of slaves. The decision also established that contracts for the sale of slaves were not contrary to public policy.

In Evans v. Patterson, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving an African American plaintiff and white defendant. The majority opinion held that the state court did have jurisdiction in this case because it involved citizens of the same state who were not protected by federal law. However, Justice Field dissented from this decision on two grounds: firstly, he argued that Congress had exclusive authority to regulate civil rights cases between citizens of different states; secondly, he argued that even if Congress did not have such authority, then any decisions made by state courts would be subject to review by federal courts under the Fourteenth Amendment's Equal Protection Clause. In conclusion, Justice Field believed that since there was no clear congressional action granting or denying jurisdiction in this particular case and since equal protection issues were at stake here due to racial discrimination against African Americans being present in some states' laws at the time - then it should be up to federal courts rather than individual states' courts alone to determine whether or not they could hear such cases as Evans v. Patterson