On why the appointments violated separation of powers:
Allowing the President to define the scope of his own appointments power would eviscerate the Constitution’s separation of powers. The checks and balances that the Constitution places on each branch of government serve as ‘self-executing safeguard[s] against the encroachment or aggrandizement of one branch at the expense of the other.’ Buckley v. Valeo, 424 U.S. 1, 122 (1976). An interpretation of ‘the Recess’ that permits the President to decide when the Senate is in recess would demolish the checks and balances inherent in the advice-and-consent requirement, giving the President free rein to appoint his desired nominees at any time he pleases, whether that time be a weekend, lunch, or even when the Senate is in session and he is merely displeased with its inaction. This cannot be the law.
On the importance of adhering to the Constitution’s original meaning:
In any event, if some administrative inefficiency results from our construction of the original meaning of the Constitution, that does not empower us to change what the Constitution commands. As the Supreme Court observed in INS v. Chadha, “the fact that a given law or procedure is efficient, convenient, and useful in facilitating functions of government, standing alone, will not save it if it is contrary to the Constitution.” 462 U.S. at 944. It bears emphasis that “[c]onvenience and efficiency are not the primary objectives—or the hallmarks—of democratic government.” Id.
The power of a written constitution lies in its words. It is those words that were adopted by the people. When those words speak clearly, it is not up to us to depart from their meaning in favor of our own concept of efficiency, convenience, or facilitation of the functions of government. In light of the extensive evidence that the original public meaning of “happen” was “arise,” we hold that the President may only make recess appointments to fill vacancies that arise during the recess.