F.A. Hayek, The Road to Serfdom

In fact, as planning becomes more and more extensive, it becomes regularly necessary to qualify legal provision s increasingly by reference to what is "fair" or "reasonable"; this means that it becomes necessary to leave the decision of the concrete case more and more to the discretion of the judge or authority in question. One could write a history of the decline of the Rules of Law, the disappearance of the Rechtsstaat, in terms of the progressive introduction of these vague formulas into legislation and jurisdiction, and of the increasing arbitrariness and uncertainty of, and the consequent disrespect for, the law and the judicature, which in these circumstances could not but become an instrument of policy.

[Chapter Six: Planning and the Rule of Law]