Thanks for clarifying for me! I can now better appreciate your earlier comment, regarding enforcement, and why you referenced the state.

I am not particularly schooled regarding voluntarism, but several mechanisms suggest themselves as equal to the task of enforcement, for example, juries. Perhaps the most important democratic mechanism, at least in America, is the jury of peers, who are empowered to decide matters at law. While most people think Judges have that job, it is rather the job of the Judge to be a specialist in the letter of the law, and to direct the technical and administrative matters relevant to a given case, so that juries, which are not expected to have legal backgrounds, can decide the merits of the case.

Just as juries in the USA are drawn from pools of eligible voters, and compensated (a little bit, anyway) for their time, it seems to me that in a stateless society eligible persons could apply to serve on juries. I have read exegeses on how courts might be entirely privately owned affairs in Libertarian states.

As it is hard to actually find examples in the USA of private prisons, for example, that aren't hopelessly intertwined with the state, and corruption, it is difficult to consider how such entities might remain uninfluenceable by those with matters before courts. Of course, courts aren't beyond influence now, so it may be that courts, particularly criminal courts, might ever be beyond influence.

Arbitration is also a mechanism potential to resolving contractual disputes, that presently is at least largely conducted by private parties. In both these examples the mechanism for resolving disputes could easily be specified in the contract itself, rather than imposed afterwards by some authoritative body, and even include buggy whips at 50 paces, if so desired by the parties thereto.