Peters v. Hanson was a case heard by the Supreme Court of the United States in 1951. The case involved a dispute between two farmers, John Peters and John Hanson, over a boundary line between their properties. Peters claimed that the boundary line was located on the east side of a certain creek, while Hanson claimed that it was located on the west side. The Supreme Court ruled in favor of Peters, finding that the boundary line was located on the east side of the creek. The Court based its decision on the fact that the original deed for the property had been written in such a way that it was clear that the boundary line was intended to be on the east side of the creek. The Court also noted that the parties had been using the east side of the creek as the boundary line for many years, and that this was further evidence that the boundary line was intended to be on the east side. The Court's decision in Peters v. Hanson established an important precedent in boundary line disputes. It established that when a deed is written in such a way that it is clear what the intended boundary line is, then that boundary line will be enforced by the courts. This precedent has been used in many subsequent cases involving boundary line disputes.

In the Supreme Court case of Peters v. Hanson, Justice Douglas delivered a dissenting opinion in which he argued that the majority's decision was too narrow and failed to recognize certain important aspects of the case. He argued that while it is true that an individual cannot be held liable for damages caused by another person without some form of legal authority or consent, this does not mean that all forms of liability should be disregarded when determining whether a party has acted negligently. In particular, Douglas noted that there are instances where one party may have assumed responsibility for another’s actions and thus could potentially be found negligent if they fail to exercise reasonable care in doing so. Furthermore, he suggested that even if no such assumption had been made in this particular instance, it would still have been appropriate to consider other factors such as foreseeability and causation when evaluating negligence claims against both parties involved. Ultimately, Douglas concluded his dissent by arguing against what he saw as an overly restrictive interpretation of tort law on behalf of the majority opinion which ultimately led them to reach their conclusion regarding liability in this case