A central issue was neglected in the last post, relating to why conflict of law rules are of such importance and concern in the development of voluntary law. Conflict of law is critical in voluntary law systems, because voluntary law systems are the only legal systems that permit each participant to choose their own law, guided by their own moral preferences and self interests.
One of the most fundamental questions concerning voluntary law is whether a system permitting self-selection of law can provide equivalent or superior justice to systems that impose laws through the exercise of power by an elite class of persons, a.k.a. statist legal systems. In statist legal systems, although many laws are imposed in the self-interest of a governing elite and those who support them, some portion of the laws are imposed in the public interest. Even a slave master may enforce rules forbidding the slaves from mistreating one another. Statist systems must deal with the problem of limiting corruption of the law caused by self-interest of elite law makers, but are not faced with the problem of harmonizing self-selected laws because they do not permit such laws to exist.
The limiting principles on self-adoption of law in voluntary law systems are non-aggression, equality of persons, and reciprocity. The primary purpose of conflict of law rules are to implement reciprocity so as to optimize fairness and stability of the system as a whole. While each person can select their own law guided by their individual self interest, the general principle of reciprocity provides that when bringing a claim or raising an affirmative defense, each person is limited by the selection of law of the other party.
Despite the importance of the reciprocity principle, it should not be forgotten that the core voluntary law principles of non-aggression and equality of persons are also limiting principles on enforceability of self-selected law. These core principles deserve expression in the form of a rule, and more attention to be paid in a later post.