Thomas Ap Catesby Jones was the plaintiff in error in a Supreme Court case against the United States. The case revolved around whether or not Jones had violated an act of Congress by entering California and taking possession of San Francisco Bay without permission from Mexico, which at that time still held sovereignty over California. The court determined that although it was true that Mexico did hold sovereignty over California, they were unable to enforce their laws due to the Mexican-American War. Therefore, since there was no effective government present in California when Jones entered and took possession of San Francisco Bay, he could not be found guilty for violating any law as there were none applicable at the time. As such, his conviction for violating an act of Congress was overturned and he was acquitted on all charges brought against him by the United States.

In Thomas Ap Catesby Jones v. The United States, the Supreme Court was tasked with deciding whether or not a naval officer could be held liable for damages caused by his orders to fire upon Mexican vessels in 1846 during the Mexican-American War. Justice McLean dissented from the majority opinion that found no liability on behalf of Jones and argued that he should have been held responsible for his actions as an agent of the government. He reasoned that since Congress had declared war against Mexico, it was within their power to determine how hostilities were conducted and thus they could hold officers accountable if they acted outside of those parameters. Furthermore, he noted that even though there may have been some uncertainty surrounding international law at this time, it did not excuse Jones’s behavior which resulted in significant damage to property belonging to foreign nationals who were not engaged in any hostile acts towards America at the time. As such, McLean concluded that while war is often chaotic and uncertain situationally speaking; when it comes down to individual responsibility for one's actions - especially when acting under color of authority - then justice must prevail regardless of circumstance or consequence