In O'Reilly & Another v. Campbell & Others, the United States Supreme Court was asked to decide whether a contract between two parties was valid and enforceable. The contract in question was an agreement between O'Reilly and Campbell, in which O'Reilly agreed to pay Campbell a certain sum of money in exchange for the right to use a patent owned by Campbell. The Supreme Court held that the contract was valid and enforceable, and that O'Reilly was obligated to pay the agreed-upon sum. The Court reasoned that the contract was valid because it was supported by consideration, meaning that both parties had given something of value in exchange for the other's promise. In this case, O'Reilly had promised to pay Campbell a certain sum of money, and Campbell had promised to give O'Reilly the right to use his patent. The Court also held that the contract was enforceable, meaning that O'Reilly was obligated to pay the agreed-upon sum. In conclusion, the Supreme Court held that the contract between O'Reilly and Campbell was valid and enforceable, and that O'Reilly was obligated to pay the agreed-upon sum.

In O'Reilly & Another v. Campbell & Others, the Supreme Court was asked to decide whether a contract between two parties should be enforced even though it had been made without consideration. The majority opinion held that the contract could not be enforced because there was no consideration given for it; however, Justice Field dissented from this decision. He argued that contracts do not necessarily need to have consideration in order for them to be enforceable and pointed out that courts have traditionally recognized certain types of agreements as valid despite their lack of consideration. Furthermore, he noted that if a party has already performed under an agreement then they should still receive some benefit from it regardless of whether or not there is any actual legal obligation on the other side to perform its part of the bargain. In conclusion, Justice Field believed that since one party had already acted upon his promise and relied upon receiving something in return then he ought to receive what was promised him by law even if there wasn't any initial exchange involved when making the agreement itself.