All agree that the phrase "the recess of the Senate" covers inter-session recesses. The question is whether it includes intra-session recesses as well.
NLRB v. Canning, p. 9
All agree that the phrase applies to vacancies that initially occur during a recess.
NLRB v. Canning, p. 21
The third question concerns the calculation of the length of the Senate's "recess." On December 17, 2011, the Senate by unanimous consent adopted a resolution to convene "pro forma session(s)" only, with "no business ... transacted," on every Tuesday and Friday from December 20, 2011, through January 20, 2012. 2011 S.J. 923. At the end of each pro forma session, the Senate would "adjourn until" the following pro forma session. Ibid. During that period, the Senate convened and adjoured as agreed. It held pro forma sessions on December 20, 23, 27, and 30, and on January 3, 6, 10, 13, 17, and 20; and at the end of each pro forma session, it adjourned until the time and date of the next. Id., at 923-924; 158 Cong. Rec. S1-S11.
The President made recess appointments before us on January 4, 2012, in between the January 3 and the January 6 pro forma sessions. We must determine the significant--that is, whether, for purposes of the Clause, we should treat them as periods when the Senate was in sessions or as periods when it was in recess. If the former, the period between January 3 and January 6 was a 3-day recess, which is too short to trigger the President's recess-appointment power, see supra, at 19-21. If the latter, however, then the 3-day period was part of a much longer recess during which the President did have the power to make recess appointments, see ibid.
...
In our view...the pro forma sessions count as sessions, not periods of recess. NLRB v. Canning, p. 33-34
Given our answer to the last question before us, we conclude that the Recess Appointments Clause does not give the President the constitutional authority to make the appointments here at issue. Because the Court of Appeals reached the same ultimate conclusion (though for reasons we reject), its judgment is affirmed.
It is so ordered.
NLRB v. Canning, p. 41