The realization that the functional concepts of the doctrine of the separation of powers were inadequate to describe and explain the operations of government was heightened by the emerging awareness of the nature of bureaucracy. The impact of Prussian bureaucracy upon the nineteenth-century writers, the establishment of a non-political civil service in England, the dissatisfaction with the spoils system in the United States, and the development of the Weberian theory of bureaucracy, led to a complete reassessment of the “executive” function. Thus the demand for the establishment of “harmony” between legislature and government, which characterized the theory of parliamentary government in Britain and France, and the Progressive movement in the United States, was accompanied by a new “separation of powers”—that between the “political” branches of government and the bureaucracy. The distinction between “Regierung” and “Verwaltung,” or between “politics” and “administration” was, paradoxically, to open a new chapter in the establishment of semi-autonomous branches of government in an age which stressed unity and cohesion.
The credibility of the doctrine of the separation of powers, particularly in the extreme forms that had characterized the Constitution of Pennsylvania in 1776, or the Constitution of France in 1791,2 already diminished by these social and institutional developments, was further undermined by the new approaches to the study of politics which characterized the twentieth century. If not everyone was prepared to relegate the study of political institutions to the sphere of mere “superstructure” that Marxist thought seemed to demand, the new concentration upon the “real forces” of politics, upon economics and class interest, led to a discounting of theories that seemed concerned only with constitutional and legal considerations. The now discarded theory of mixed government had at least had a social basis for its view of a desirable governmental system, whereas the separation of powers had, quite deliberately, been formulated as a constitutional theory devoid of class bias. There was a diminution of belief in the efficacy of constitutional barriers to the exercise of power, and students of politics demonstrated how legal rules could be evaded or employed to produce an effect directly opposite to that intended. A concentration upon the facts of “politics” rather than of law, leading to a concern with political parties and pressure-groups, directed attention away from the role of constitutions in the political system. The general attack upon “political theory,” which suggested that it was merely the expression of opinion or prejudice, tended to depreciate those theories that historically had been strongly empirical in content, along with more metaphysical philosophizing. It was suggested that it was not possible to deduce from a general theory of politics specific unequivocal solutions to particular problems, and that therefore it was probably more fruitful to adopt a pragmatic approach to these individual problems, rather than to attempt wide-ranging generalizations.
The weight of the attack upon the doctrine of the separation of powers was thus seemingly overwhelming. Yet the examination of the history of the doctrine is not merely an academic exercise, of historical interest only. In spite of the attacks upon the form, and upon the content, of the doctrine there is a sense in which the problems the theorists of the separation of powers set out to solve are more than ever critical today. The recognition of the fact that modern society must meet demands unknown in earlier centuries may make the form of the earlier doctrine irrelevant, but the values it represented are still an essential part of the content of “Western democracy.” An examination of the history of the past centuries reveals that for all its inadequacy there is a stubborn quality about the doctrine of the separation of powers. It persistently reappears in differing forms, often in the very work of those who see themselves as its most bitter critics. As will be suggested at a later stage, this is no mere coincidence; it is a recognition of the fact that in some form, a division of power, and a separation of function, lie at the very heart of our systems of government. An idea that finds its roots in ancient constitutionalism, and which in the seventeenth century became a central feature of a system of limited government, has obviously to be reformulated if it is to serve as an instrument of modern political thought, but it can only be rejected altogether if we are prepared to discard also the values that called it into being. The study of the history of constitutional theory can show us, therefore, the extent to which the doctrine remains important, and the extent to which the concepts upon which it rests have become outmoded. The importance of such an investigation hardly needs to be stressed, when we recall that the current institutional structures of two of the three countries with which we are here concerned are overtly based upon the acceptance of the doctrine of the separation of powers; and it will be argued that an approach to the study of British government that rules out all reference to the “separation of powers” is an inadequate one.
But what is “constitutional theory”? It is at once both more than and less than the study of political institutions. It is based upon the assumption that not all States are “constitutional regimes,” for in the constitutional State there must be a set of rules which effectively restrains the exercise of governmental power. “Constitutionalism” consists in the advocacy of certain types of institutional arrangement, on the grounds that certain ends will be achieved in this way, and there is therefore introduced into the discussion a normative element; but it is a normative element based upon the belief that there are certain demonstrable relationships between given types of institutional arrangement and the safeguarding of important values. Thus on the one hand constitutional theory has to grapple with the problems of the existence of nominal or façade constitutions, and on the other with the assumptions implicit in the extreme versions of the modern behaviourist approach, which, with its emphasis upon informal processes, tends to suggest that formal structures have little or no significance.3 It is therefore a type of political theory that is essentially empirical, yet which overtly recognizes the importance of certain values and of the means by which they can be safeguarded. Yet in this respect perhaps constitutionalism and constitutional theory are not so far removed from the general stream of political science as might at first be supposed. In the twentieth century the study of politics has become more empirically oriented, less overtly concerned with the justification of particular patterns of values. Nevertheless, the close relationship between the description and explanation of political institutions and of the justification of the values they reflect is an inescapable one. However strong the urge towards objectivity on the part of the student of politics, it is impossible for his work to be wholly detached from the problem of what is a “just,” “desirable,” or “efficient” political system, for the work must inevitably reveal the values that infuse the politics of the countries he studies and the results which their political systems produce. The more theoretical and general his approach the more likely he is, even if only through the means of classification he adopts, to take up a stance of approval or disapproval. This can be seen very clearly in many modern American works on political science.4 There is, in fact, a complex inter-relationship between the study of political institutions and the justification of particular types of governmental systems.
The doctrine of the separation of powers was for centuries the main constitutional theory which claimed to be able to distinguish the institutional structures of free societies from those of non-free societies. It was by no means a value-free or neutral theory of politics, but it did claim to be based upon a demonstrable empirical proof. In the mid twentieth century, however, the doctrine has largely been rejected, either as a prescription for the creation of an efficient, free system of government suited to modern circumstances, or as a set of concepts which provides a useful vocabulary for the investigation and description of systems of government. Yet little has been offered in place of this relatively coherent body of political doctrine as a framework for the analysis of political systems. Indeed, the modern attempts to provide generalized statements about the articulation of the parts of government depend very heavily upon just those concepts of function and balance which characterized earlier constitutional theories. Clearly, however, the extent to which these earlier constitutional theories concentrated attention upon the formal structures of government, especially upon the formal relationships between executive, legislature, and judiciary, made it impossible to handle effectively the problems of distinguishing nominal from effective constitutions, and failed to give a complete picture of “constitutional government” in operation. A discussion of the nature