Ambler v. Choteau was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved a contract between the plaintiff, Ambler, and the defendant, Choteau, in which Ambler agreed to pay Choteau a certain sum of money in exchange for a tract of land. Ambler paid the money, but Choteau refused to convey the land. Ambler then sued Choteau for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was in writing and that both parties had signed it. The Court also noted that Ambler had paid the money as agreed and that Choteau had not provided any evidence that the contract was invalid. Therefore, the Court held that the contract was valid and enforceable and that Ambler was entitled to the land.

In Ambler v. Choteau, the Supreme Court was tasked with determining whether a contract between two parties that had been made in Indian Territory (now Oklahoma) was valid under federal law. The majority opinion held that the contract did not have to be approved by Congress and could therefore be enforced as it stood. Justice Field dissented from this decision, arguing that because of its location within Indian Territory, any contracts entered into there must receive congressional approval before they can be enforced according to federal law. He argued further that even if such contracts were enforceable without congressional approval, they would still need to comply with applicable tribal laws or customs in order for them to remain valid and binding on both parties involved. In conclusion, Justice Field believed that due to the unique circumstances surrounding this case – namely its location within Indian Territory – Congress should have been consulted prior to enforcing the agreement between Ambler and Choteau