“The principle of organization of government on the basis of “separate” departments is not only fundamental in the structure of American Federal government, but it has been written into every one of our state constitutions in one form or another.
That purpose was stated in Article XXX of the Declaration of Rights of the Massachusetts Constitution to be the achievement of “a government of laws, and not of men.” In another article the same purpose was stated more fully in the following words: “Government is instituted for the common good;—and not for the profit, honor, or private interest of any one man, family, or class of men.”
“The separation of departments had a well-understood meaning to Massachusetts constitution makers, and it was incorporated in the Constitution of 1780 for a practical purpose. This study seeks to show that the primary purpose of the constitutional statesmen in adopting the principle was in reality not a “differentiation of the functions and organs of government,” for discussion of differentiation of the functions of government was negligible at the time. What they actually sought to ensure was the independence of action of the various branches of government or departments: they did not have in mind a separation of powers into different types of power in the modern sense, nor any absolute separation of departments. In the eighteenth century the chief problem in connection with the separation of departments was a separation in office-holding, for which they went back to the common-law rule against the holding of incompatible offices and the English place bills. Neither was the separation of departments, as modern students have supposed, an end in itself. The examination made in this study of the meaning and purpose of the organization of powers in separate departments in Massachusetts in the colonial period has shown that not only was the principle possible of execution in terms of the colonial understanding of it, but that its execution became so universal in the early Massachusetts state government that it was then very much taken for granted. Today political scientists for lack of consecutive discussion have lost sight of the ends which the constitutional framers had in view, their reasons for adopting the principle, and their interpretation of it.”
“It will also be seen that the separation of departments, far from being a check to the majority as is sometimes said, actually was looked upon by the constitutional fathers of Massachusetts as their most important protection against an oligarchy and as a guarantee of government for the benefit of all groups of the state, although not, of course, for the benefit of the majority alone. The study, it is believed, will show that the purpose which the constitutional statesmen of Massachusetts had in mind was to establish a “government of laws and not of men,” that is, a government which would function in the public interest. This end they sought to achieve through a separation of departments.
English constitutional experience and theory and the common-law rule against incompatible offices have hitherto been much neglected as an influence in American constitution making. Actually, for decades prior to the Revolution, the separation of departments was something more than a theory to the Massachusetts colonists. That the principle was necessary to insure effective checks and balances in the public interest was demonstrated to them, not only by their own experience, but also by the statutes and common law of England. In the mother country, the Revolution of 1688 with its constitutional changes was conceived to have furthered greatly the separation, or independence, of the departments” and to have resulted in provisions for this purpose not only in the Act of Settlement (since important provisions in that Act were never enforced) but also in a long series of subsequent statutes. In adopting the principle, therefore, the Massachusetts constitution makers looked upon it as something which had already been achieved in England by the common law, by the Act of Settlement and by the various place bills, the passage of a series of which began in 1693 and continued for the greater part of the eighteenth century.
In her first state constitution, Massachusetts adopted a threefold statement of the principle of a separation of departments. The experience which called for such a thrice-certain guarantee went back not only to the beginnings of Massachusetts government, but also to the constitutional struggles of the mother country. The “government of men,” which the Constitution of 1780 provided against, had flourished in Massachusetts from the earliest days of the colony, but the practice of combining important offices of state in the hands of a few men was a custom of long standing in England before it was transplanted to Massachusetts. From the colony period (1629-1692), the “government of men” was carried down in Massachusetts (but with some differences) into the province government set up by the Charter of 1691.
The Trading Company Charter of 1629 had given the Massachusetts Bay Company a Governor annually elective by the General Court, which was a body made up of all the members of the Company. During this colony period, the annually elective Governor was merely primus inter pares,” his fellow magistrates (the Assistants) like him acting in an administrative and judicial body of the company known as the Court of Assistants, and constituting also the County Courts and the Council of the Magistrates. They also were members of the General Court. Quite otherwise under the Charter of 1691, the Governor was removed from popular influence by being made appointive by the Crown, while new powers given by the Charter established him as the chief magistrate of the province.”
Brennan, Ellen Elizabeth. Plural Office-holding In Massachusetts, 1760-1780: Its Relation to the “separation” of Departments of Government. Chapel Hill: The University of North Carolina Press, 1945. https://babel.hathitrust.org/cgi/pt?id=mdp.39015008733639&view=1up&seq=7