In law, the duty to retreat, or requirement of safe retreat, is a legal requirement in some jurisdictions that a threatened person cannot harm another in self-defense (especially lethal force) when it is possible instead to retreat to a place of safety.
Carrying weapons
As to carrying weapons in anticipation of an attack, Evans v Hughes held that for a defendant to justify his possession of a metal bar on a public highway, he had to show that there was an imminent particular threat affecting the particular circumstances in which the weapon was carried. Similarly, in Taylor v Mucklow a building owner was held to be using an unreasonable degree of force in carrying a loaded airgun against a builder who was demolishing a new extension because his bills were unpaid. More dramatically, in AG's Reference (No 2 of 1983) Lord Lane held that a defendant who manufactured ten petrol bombs to defend his shop during the Toxteth riots could set up the defense of showing that he possessed an explosive substance "for a lawful purpose" if he could establish that he was acting in self-defense to protect himself or his family or property against an imminent and apprehended attack by means which he believed to be no more than reasonably necessary to meet the attack.
United States law
[[File:Stand-your-ground law by US jurisdiction.svg|thumb|275x275px|Stand your ground law and duty to retreat by US jurisdiction
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Most U.S. jurisdictions have a stand-your-ground law or apply what is known as the castle doctrine, whereby a threatened person need not retreat within his or her own dwelling or place of work. Sometimes this has been the result of court rulings that one need not retreat in a place where one has a special right to be. In other states, this has been accomplished by statute, such as that suggested by the Model Penal Code.
In Erwin v. State (1876), the Supreme Court of Ohio wrote that a "true man", one without fault, would not retreat. In Runyan v. State (1877), the Indiana court rejected a duty to retreat, saying,