Reed v. United States was a Supreme Court case in which the Court held that the United States government was not liable for damages caused by the negligence of its employees. The case arose when a steamboat owned by the United States government collided with a vessel owned by the plaintiff, causing damage to the plaintiff's vessel. The plaintiff sued the United States government for damages, arguing that the government was liable for the negligence of its employees. The Supreme Court held that the United States government was not liable for the negligence of its employees. The Court reasoned that the government was not liable for the negligence of its employees because the government was not a common carrier and did not owe a duty of care to the plaintiff. The Court also held that the government was not liable for the negligence of its employees because the government was not engaged in a business that was subject to the same rules of liability as private businesses. The Court's decision in Reed v. United States established the principle that the United States government is not liable for the negligence of its employees. This principle has been applied in numerous cases since then, and it remains an important part of the law today.

In Reed v. United States, the Supreme Court was asked to decide whether a federal statute that prohibited certain types of lottery tickets from being transported across state lines violated the Commerce Clause of the Constitution. The majority opinion held that Congress had authority under the Commerce Clause to regulate interstate commerce and thus could prohibit such transportation. Justice Field dissented, arguing that while Congress did have some power over interstate commerce, it should not be able to use this power in an arbitrary manner or for purposes unrelated to regulating trade between states. He argued that prohibiting lottery tickets from crossing state lines would do nothing to promote free trade among states and instead only served as a way for Congress to interfere with activities within individual states without any legitimate purpose related to regulating interstate commerce.