Indeed, principles leave an open window to adapt judgments in case of changing circumstances and thus, need less frequent changes which would spread out confusion. But we have to be conscious that principles ought to lead to rules just like a constitution needs laws to be effective.
The constitution of the Soviet Union, which was considered as one of the most democratic, went unheeded due to the gap in practice between this constitution and laws. 2. Of course, there are differences between private and public rules, only the latter benefiting from the monopoly of forceful implementation. Principles may also have private or public sources.