It’s a common trope in Western films and books: The wanted poster that mentions that the fugitive is wanted “dead or alive”. Was that ever really a thing? It sounds like medieval-style outlawry, whereby individuals forfeit their right to protection under the law and may be harmed or even killed by anybody with impunity. How could that work in a legal system that was operating under the U.S. constitution, and how could a government operating in that system openly incite people to kill someone outside a proper trial?
Yes, there are plenty of examples of posters with the words “Dead or Alive” printed on them.
However, of course it’s not as simple as that. These posters were NOT a “free murder license.” See the Ford brothers who killed Jesse James. They were his friend and arranged with the governor to bring him in for the reward money. They ate breakfast with the man then shot him in the back of the head. They went to collect their reward and were instead arrested for murder (the governor eventually pardoned them).
Now, if there’s no witnesses, it’s your word against the dead man’s, but if there are witnesses you’d better be prepared to prove self-defense.
Or, at least be able to produce enough witnesses that will vouch for your story.
Film, television, and dime novel representations of the “Old West” tend to overemphasize the amount of violent crime and “killin’” but in the American Frontier expansionist period (essentially, from the Louisiana Purchase until the the 1890s) there was essentially no law outside of municipalities. Note that as a private citizen you couldn’t legally just put up a “Wanted” poster; those were issued by a US District Court which had traveling judges who reviewed cases, issued fugitive warrants, and authorized bounties. The “Wanted Dead or Alive” was just a recognition of the difficultly of retrieving a violently resisting fugitive along a trek of many days.
US Marshals were individuals given license by a district judge to enforce court orders, retrieve fugitives, and deputize whomever they needed to do the same. Because of the impracticality of transporting a violent living fugitive much less a gang, Deputy US Marshals were often empowered to kill a fugitive as necessary; the same did not apply to ordinary citizens or territorial residents who were not deputized or authorized by the court. Deputies were often paid by bounty rather than receiving a salary, and the service often attracted previous criminals and gang members but even then there were rarely enough deputies to seek out fugitives (bank robbery and cattle rustling were the two most common crimes) resulting in the rise of bounty hunters who were most often former slave hunters who moved out West to practice their trade after the Civil War and abolition.
The “Indian Wars” of the mid-to-late 19th Century and property fights between miner, farmers, and free range cattle owners resulted in push toward statehood (and had a lot to do with the women’s suffrage movement as many Western states offered women voting rights as an inducement to move West). Once territories achieved statehood they were carved into counties in a fashion similar to that of English law with a “sheriff” (from the Anglo-Saxon shire-reeve, an administrator responsible for magisterial duties such as defining property boundaries, overseeing peasants, collecting taxes, et cetera) whose duties quickly evolved to law enforcement role and marshals became less common, only called upon for fugitives crossing state lines or into territories. With the erection of more jails and local law enforcement the impetus to allow enforcement officers to arbitrarily kill fugitives mostly disappeared.
Today, of course, it is illegal for a US Marshal or other law enforcement officer to execute a fugitive or suspect; they are only supposed to use deadly force in the case of self-defense, defense of public threat, or to prevent a violent fugitive from escaping custody. However, the police effectively have sweeping powers and protections against civil suit in the form of sovereign immunity or qualified immunity against being held personally accountable for excessive use of force, and the United States has the highest rate of police violence and shootings of any liberal democracy, in no small part because of some of the legal traditions stemming from the frontier period.
Stranger
“Dead or alive” doesn’t mean you can just murder folks without punishment. It means that if you are trying to capture the person and they attack you, and you kill them in self-defense, you are still able to collect the reward. But if you sneak up and kill them, then deliver the body, you are a murderer and when you drop off the body you are delivering two criminals into the custody of law enforcement. (The dead body and yourself.)
A pardon takes care of those pesky murder charges though. 