Vagabund

If this occurs under one state system or another, the answer is simple: responsibility lies with whoever is legally required to bear it. Usually, this turns out to be the judge and the taxpayers, or only the taxpayers. Additionally, false witnesses and other individuals involved in fabricating the sentence may also be caught in the gears.

But the question, I presume, concerns ancap, that is, a social order in which law enforcement is decentralized, and developed commodity-money relations are in effect.

Are courts possible under ancap? Yes, because conflicts are possible, and the service of resolving them through a verdict by a third party not involved in the conflict may be in demand on the free market. Are courts that issue death sentences possible under ancap? As a procedure implying the voluntary participation of each party—it is quite doubtful, since the party who may be threatened with the death penalty by a court verdict has a strong incentive to simply refuse to participate in the court.

Are courts that issue verdicts in conditions where one of the parties does not recognize the jurisdiction of that court over them possible under ancap? They are. When I speak of possibility, I mean potential market demand under ancap conditions.

Such a court can function in two ways.

First, it can examine evidence of a crime in a situation where the criminal is in hiding, and give the go-ahead for their pursuit and retribution by any means convenient to the plaintiff. Why does the plaintiff need this? So that other people can familiarize themselves with the verdict and not obstruct this pursuit.

Second, the plaintiff can independently detain the defendant and forcibly bring them before the court. Why? So that the execution they intend to carry out is favorably accepted by those around them and not viewed as some kind of lawlessness.

Can a verdict of guilt be appealed? Yes, of course. The pursued party can present evidence of their innocence to another court, or even to the same one, and after reviewing it, the court may issue a verdict of innocence in light of newly discovered circumstances. If the plaintiff is not satisfied with this new verdict, they will have to act further without the support that the court decision provided, which could be critical for the ability to carry out the execution.

And what if the plaintiff has already executed the defendant using a court verdict, and then evidence of their innocence surfaces? That is, for example, some third party obtains the evidence and deems it important to make it public, after which one or several courts review it and issue an acquittal. By the way, will they do this if they aren’t paid? Actually, they have a market motive: if they can show that the court which issued the verdict of guilt was biased and conducted the procedure incorrectly, they will bury their competitor.

Thus, under ancap, the judge, the plaintiff, and those who execute the court’s decision (if the plaintiff does not carry out the death sentence personally) act at their own peril and risk, and bear responsibility to the extent that other interested parties are willing to spend effort to hold them accountable. Vague? There’s nothing to be done; decentralized systems rely on market incentives, not direct mandates. Just look at Bitcoin—that’s all it relies on, and, you must agree, it’s working out quite well.