In O'Hara et al. v. MacConnell et al., Assignees, the Supreme Court of the United States was asked to decide whether a contract between two parties was valid and enforceable. The contract in question was between O'Hara and MacConnell, and it stated that O'Hara would pay MacConnell a certain sum of money in exchange for a certain amount of goods. MacConnell had assigned the contract to two other parties, and O'Hara argued that the assignment was invalid and that he was not obligated to pay the money. The Supreme Court held that the assignment was valid and that O'Hara was obligated to pay the money. The Court reasoned that the assignment was valid because it was made in good faith and with the consent of both parties. Furthermore, the Court held that the assignment was binding on O'Hara because he had accepted the goods and had not objected to the assignment. As a result, the Court held that O'Hara was obligated to pay the money as agreed in the contract.

In O'Hara et al. v. MacConnell et al., Assignees, the Supreme Court was asked to decide whether a contract between two parties could be enforced after it had been assigned by one of them to another party who was not aware of its terms at the time they accepted it. The majority opinion held that such contracts were enforceable and that assignees should take notice of any existing contractual obligations when accepting an assignment from another party. Justice Field dissented, arguing that this would create an unfair burden on assignees since they are unable to investigate every potential obligation before accepting an assignment and thus may unknowingly accept responsibility for liabilities which do not exist in their own right but rather belong solely to the original contracting parties. He argued instead for a more equitable solution whereby both sides must agree upon all relevant terms prior to assigning or transferring any rights or responsibilities under a contract so as to protect innocent third-parties from being unfairly burdened with unknown obligations without their consent or knowledge