In my last post, I noted that the advocates of departmentalism do not rely on pre-constitutional practice to found their view. Instead, they tend to argue that the Constitution adopted a new system, one in which each of the branches is equally entitled to interpret the Constitution.
The problem with this argument is that it lacks support. The Constitution both relied upon the preexisting English and state systems as well as establishing some innovations. The question for departmentalists is to show that the Constitution actually adopted departmentalism.
Here is what I regard as the basic textual problem with arguing that the new system established departmentalism: the Constitution typically used terms that had their historical or common law meanings. Thus, when the Constitution used the term “judicial power” or “executive power” it typically meant those terms to have their traditional meanings.
That does not mean that the Constitution retained the entire traditional system. It clearly established a new system in certain ways, but it did so by changing the rules governing these entities, not by using the traditional terms in a new way.
Let me provide an example. The Constitution diminished the powers of the President from those of the King. But it did not do this simply assuming that the term “executive power” would have a new meaning. Instead, it vested the executive power in the President, but then took away or constrained various powers that the King had. So it gave the Congress the King’s power to declare war. And it constrained the King’s unilateral power to make executive appointments by giving the President the power to appoint officers only with the consent of the Senate. It did these things expressly rather than by assuming that readers would understand that the system had been changed.
Thus, if departmentalism were to be adopted by the Constitution, it would occur through provisions in the Constitution that would adopt it. But I am not aware of any such provisions.
That the Constitution is the supreme law of the land and that each branch is required to follow it do not do the trick. That the Constitution is the supreme law does not prevent courts from the obligation to follow judicial precedent if, as I have argued, precedent is either required by the Constitution or if the Constitution treats it as a matter of federal common law. Similarly, that the Constitution requires each branch to follow it does not prevent the other branches from also having to follow judicial precedent if, as I have suggested might be true, such an obligation is either required by the Constitution or it the Constitution treats it as a matter of federal common law.