This case was a dispute between the executor of the estate of a deceased man, Moran, and the City of New Orleans. The dispute centered around a contract between the deceased man and the City of New Orleans. The deceased man had contracted with the City to build a levee, and the City had agreed to pay him for his work. However, the City had failed to pay the deceased man for his work, and the executor of his estate, Moran, was now seeking payment. The Supreme Court ruled in favor of Moran, finding that the City of New Orleans had breached its contract with the deceased man and was liable for the payment of the contract. The Court held that the City was obligated to pay the executor of the deceased man's estate the amount due under the contract. The Court also held that the executor was entitled to interest on the amount due, as the City had failed to pay the deceased man for his work. In conclusion, the Supreme Court found that the City of New Orleans had breached its contract with the deceased man and was liable for the payment of the contract. The Court also held that the executor of the deceased man's estate was entitled to interest on the amount due, as the City had failed to pay the deceased man for his work.

In Moran, Ex'r of Cooper v. New Orleans, the Supreme Court was asked to decide whether a state tax on foreign insurance companies violated the Constitution's Commerce Clause. The majority opinion held that it did not violate this clause because Congress had not yet regulated such taxes and thus states were free to do so. Justice Field dissented from this decision, arguing that while Congress had not specifically addressed these types of taxes in its legislation, it still should be considered an interference with interstate commerce as defined by the Commerce Clause. He argued that since insurance is an activity which crosses state lines and affects multiple states at once, any taxation imposed upon it should be done uniformly across all states or else risk creating economic imbalances between them. Furthermore he noted that if each individual state could impose their own regulations on foreign insurers then they would have no incentive to enter into agreements with other states for uniformity in taxation or regulation - something which would ultimately harm interstate commerce rather than promote it as intended by the Constitution's framers.