Last night an unusual event happened at the White House. Chief Justice John Roberts re-administered the presidential oath of office to Barack Obama, a day and a half after they had performed the same ritual rather shakily in the inaugural ceremony. White House counsel Gregory B. Craig explained: "We believe that the oath of office was administered effectively and that the president was sworn in appropriately yesterday. But the oath appears in the Constitution itself, and out of an abundance of caution, because there was one word out of sequence, Chief Justice Roberts administered the oath a second time."

What was that one out-of-sequence word? Faithfully.

Justice Roberts misplaced the word faithfully when stating the official oath, which asks the president-elect to swear that he "will faithfully execute the office of President of the United States." Faithfully got removed from the spot between will and execute in Roberts' rendering, moved to the end of the clause. Then, when Obama hesitated, Roberts tried again, placing faithfully immediately after execute. Obama ended up saying it the first (wrong) way, with faithfully at the end. (For a fuller analysis, see my post-inaugural piece on Language Log. To my surprise, this technical linguistic treatment was picked up by everyone from Andrew Sullivan and AOL News to The Guardian and The Telegraph.)

On the op/ed page of the New York Times, linguist Steven Pinker hazards a guess as to why Justice Roberts, working without any written prompts, ended up removing faithfully from its rightful place in the Constitution's phrase "will faithfully execute." Roberts is famous for being a grammatical stickler, and during the administration of the oath "his inner copy editor overrode any instincts toward strict constructionism and unilaterally amended the Constitution by moving the adverb 'faithfully' away from the verb."

But why would his "inner copy editor" do such a thing? As Pinker explains, grammatical prescriptivists have long had a problem with "split verbs" — the placement of an adverbial modifier between an infinitive or auxiliary and the main verb in a sentence. This gripe is most widely recognized in the "rule" against split infinitives, a notion that arose out of trying to make English grammar conform to the model of Latin. (In Latin, the infinitive form of a verb is unsplittable, because it's a single word.)

Over on Language Log, Mark Liberman of the University of Pennsylvania has investigated the similar injunction against placing an adverb between an auxiliary and a verb — exactly what would make Roberts uneasy about saying "will faithfully execute." It's a pet peeve among law review editors, so a young John Roberts was very likely exposed to it during his legal training. (Like President Obama, Roberts was once editor of the Harvard Law Review.) Baltimore Sun copy editor John McIntyre has noted that this thinking pervades newsrooms too, despite the fact that enforcing the rule can lead to phrasing that sounds unidiomatic:

I'm particularly irritated by the journalistic taboo against putting an adverb between the auxiliary and main verb — writing always has written instead of has always written. It is not, strictly speaking, an error of grammar, but it is awkward and non-idiomatic syntax. If I have time to change it while editing, I do so, and no one has ever complained. (And if you read over has ever complained just now without finding it amiss, you see how idiomatic English is written.)

If Pinker is right about the mental editing that Justice Roberts performed on the fly, then it is of course deeply ironic for such a "strict constructionist" to amend the Constitution under the influence of what Stanford University's Arnold Zwicky has aptly named a "zombie rule." Roberts, however, owned up to his mistake at a luncheon following the inaugural ceremony, and the wheels were soon set in motion for a "do-over" to ensure that the constitutional mandate was properly followed. We can all now rest assured that the administration of the oath has been executed faithfully — and faithfully executed.