Westray v. United States was a Supreme Court case that addressed the issue of whether the United States could be held liable for the wrongful death of a soldier in the line of duty. The case arose when Private Westray was killed in a military exercise in 1864. His widow, Mary Westray, sued the United States for damages, claiming that the government was negligent in its duty to provide a safe environment for her husband. The Supreme Court held that the United States could be held liable for the wrongful death of a soldier in the line of duty. The Court reasoned that the government had a duty to provide a safe environment for its soldiers, and that it had breached this duty by failing to provide adequate safety measures. The Court also held that the government was liable for the damages caused by its negligence, and that Mary Westray was entitled to compensation for her husband's death. The Court's decision in Westray v. United States established a precedent that the United States could be held liable for the wrongful death of a soldier in the line of duty. This decision has been cited in numerous subsequent cases, and has been used to support the idea that the government has a duty to provide a safe environment for its soldiers.

Justice Field delivered the dissenting opinion in Westray v. United States, arguing that the Court should have dismissed the writ of error for lack of jurisdiction. He argued that Congress had not given this court authority to review a decision made by a military commission and therefore it was outside their power to do so. Furthermore, he noted that even if they did have such authority, there were no errors in fact or law committed by the military commission which would warrant overturning its decision. In conclusion, Justice Field believed that since Congress had not granted them jurisdiction over decisions made by military commissions and since there were no errors present in this case specifically, then it was inappropriate for them to interfere with an action taken within executive powers as established under Article II of the Constitution.