"Procedural fairness, if not all that originally was meant by due process of law, is at least what it most uncompromisingly requires. Procedural due process is more elemental and less flexible than substantive due process. It yields less to the times, varies less with conditions, and defers much less to legislative judgment. Insofar as it is technical law, it must be a specialized responsibility within the competence of the judiciary on which they do not bend before political branches of the Government, as they should on matters of policy which compromise substantive law. If it be conceded that in some way [the agency could take the action it did], does it matter what the procedure is? Only the untaught layman or the charlatan lawyer can answer that procedure matters not. Procedural fairness and regularity are of the indispensable essence of liberty. Severe substantive laws can be endured if they are fairly and impartially applied. Indeed, if put to the choice, one might well prefer to live under Soviet substantive law applied in good faith by our common-law procedures, than under our substantive law enforced by Soviet procedural practices. Let it not be overlooked that due process of law is not for the sole benefit of an accused. It is the best insurance for the Government itself against those blunders which leave lasting stains on a system of justice but which are bound to occur on ex parte consideration."