One of the most striking features of our constitutional law is the persistent purpose to protect the liberties of the people from arbitrary power by vesting the functions of sovereignty in three coördinate departments of government. This division is accomplished by express provisions in some state constitutions and by necessary implication in all constitutions, federal and state. By judicial construction the legislature may not exercise judicial or administrative powers; the executive may not exercise legislative or judicial powers, and the judiciary is denied the exercise of legislative or administrative powers. This fundamental principle of constitutional law is established by judicial decisions, both state and federal, of long standing and uninterrupted unanimity.A commission is an administrative body; may it exercise judicial functions, and if so to what extent? The question involves, first, a definition of judicial functions; second, a statement of the exceptions to the rule that judicial powers may not be exercised by the administrative department; and, third, an appreciation of the relation of judicial determinations to the regulatory powers vested in commissions. We may then consider whether or not the present scope of judicial determinations by commissions, and the court review of such determinations, are satisfactory.