Washington ? “The president shall have power to fill up all vacancies that may happen during the recess of the Senate.”

— The Constitution, Article II, Section 2

“‘When I use a word,’ Humpty Dumpty said in a rather scornful tone, ‘it means just what I choose it to mean — neither more nor less.'”

— Lewis Carroll, “Through the Looking Glass”

When on Jan. 20, 2009, Barack Obama swore to defend the Constitution, he did not mean all of it. He evidently believes that the provision quoted above merely expresses the Framers’ now anachronistic anxieties about abuses of executive power. (Jefferson’s lengthy catalog of George III’s abuses is called the Declaration of Independence.) So on Jan. 4, 2012, Obama simply ignored the Recess Clause.

He was in his “We can’t wait!” — for Congress and legality — mode, as he was when he unilaterally rewrote laws pertaining to welfare, immigration and education. On Jan. 4, he used recess appointments to fill three seats on the National Labor Relations Board, even though the Senate said it was not in recess. Obama’s cheeky Humpty Dumpty rejoinder was: I d ecide what “recess” means. Now a court must decide whether the Constitution means what it says.

In 2011, the Noel Canning company, which bottles soft drinks in Yakima, Wash., was negotiating a labor contract with Teamsters Local 760. The union says it and the company reached a verbal agreement. The company disagrees. An administrative law judge sided with the union. On Feb. 8, 2012, after Obama’s disputed appointments, the NLRB upheld that decision and asked a federal court to enforce it. Noel Canning is asking the court to declare that the NLRB’s intervention in the dispute was unlawful because the board lacked a quorum until Obama made the recess appointments, which were invalid because the Senate was not in recess.

In support of the company, Senate Republican Leader Mitch McConnell and 41 members of his caucus have filed a brief arguing that the recess appointments “eviscerated” two of the Senate’s constitutional powers: to “determine the rules of its proceedings” and to reject presidential appointments.

The Recess Clause says the president’s power extends only to vacancies that “happen” while the Senate is in recess. This does not describe the NLRB vacancies — or many vacancies filled by many presidents’ recess appointments since George Washington made the first ones in 1789. It does, however, describe the problem the Framers addressed: Until the Civil War, travel was slow and arduous, so Senate sessions usually lasted only three to six months. The Framers wrote the Recess Clause to give presidents very limited authority to fill important posts, while preserving the Senate’s absolute veto over presidential nominations.

For more than a century, it was generally accepted that recess appointments could only fill vacancies that occurred between sessions, not in recesses during sessions. Of late, however, presidents of both parties have made many recess appointments during short adjournments — as short as 10 days. To limit this, both parties when controlling Congress have adopted the practice of conducting pro forma sessions so the Senate is not in recess even while most senators are away.

It was holding such sessions every three days when Obama abandoned the settled policy of presidents respecting this practice. He treated the Senate’s unwillingnessto act on his NLRB nominations as an inability to act, and said this inability constituted a de facto recess. He disregarded the Senate’s express determinations on Jan. 3 and 6 that it was in session. And the fact that twice in 2011 the Senate, while in such pro forma sessions, passed legislation, once at Obama’s urging.

Because the Constitution unambiguously gives the Senate the power to regulate its proceedings, Obama’s opinion that the Senate was not in session when it said it was, and his assertion that it was in recess even though it held sessions on Jan. 3 and 6, has no force or relevance. And although he is a serial scofflaw, not even he has asserted the authority to make recess appointments during adjournments of three days or fewer.

The constitutional guarantee of congressional self-governance, combined with the Senate’s determination that it was in session Jan. 4, destroys Obama’s position, which is that he can declare the Senate in recess whenever he wishes to exercise what the Framers explicitly denied to presidents: a unilateral appointments power. Consider this episode when deciding whether on Jan. 20, 2013, he should again have a chance to swear to (only selectively) defend the Constitution.