To outline the fundamental differences between the legislator and the judge, I can do no better than to quote Bruno Leoni:

"First, judges or lawyers or others in a similar position are to intervene only when they are asked to do so by the people concerned, and their decision is to be reached and become effective, at least in civil matters, only through a continuous collaboration of the parties themselves and within its limits. Second, the decision of judges is to be effective mainly in regard to the parties to the dispute, only occasionally in regard to third persons, and practically never in regard to people who have no connection with the parties concerned. Third, such decisions on the part of judges and lawyers are very rarely to be reached without reference to the decisions of other judges and lawyers in similar cases and are therefore to be in indirect collaboration with all other parties concerned, both past and present.
"All this means that the authors of these decisions have no real power over other citizens beyond [that which] citizens themselves are prepared to give them by virtue of requesting a decision in a particular case.
"It means also that this very power is further limited by the unavoidable reference of every decision to decisions issued in similar cases by other judges. Finally, it means that the whole process can be described as a sort of vast, continuous, and chiefly spontaneous collaboration between the judges and the judged in order to discover what the people's will is in a series of definite instances - a collaboration that in many respects may be compared to that existing among all the participants in a free market."7