An ex-professor of constitutional law, President Obama understands an unsettling truth about executive overreach: It’s unconstitutional only if somebody squawks. Sure, the Constitution says the president can’t make an appointment without the Senate’s consent. But if he does, and nobody objects, what’s stopping him?

Now Republicans are objecting to Obama’s appointment of Richard Cordray as director of the Consumer Financial Protection Bureau. They’re demonstrating another truth: Everyone’s a strict constructionist when he’s not in power. Still, they’re right. This so-called recess appointment is unconstitutional, because the Senate wasn’t in recess when Obama made it. It was holding pro forma sessions, and, contra the Office of Legal Counsel’s memo, those do count.

Yet Obama has betrayed the original understanding of the Constitution in another sense — as did Pres. George W. Bush before him. Prof. Michael Rappaport of the University of San Diego has argued that the Constitution, as originally conceived, empowered the president to make recess appointments only to those vacancies that arose when the Senate was in recess. This vacancy, however, has existed since Obama signed the Dodd-Frank bill into law in July 2010.

If Republicans want to put teeth back into the Constitution, they should demand a return to the original understanding of the recess-appointment power in full.

First, consider the text. In Article II, Section 2, it says the “President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of their next Session.” Under current practice, the president treats the word “happen” as if it means “exist,” — that is, he makes appointments to offices that are vacant during the recess, whether or not those vacancies occurred before the recess.

This interpretation flouts the original understanding. Try this example: On April 2, 1792, Congress passed a law establishing the national mint, but Pres. George Washington failed to nominate a candidate for chief coiner before the Senate adjourned on May 8. Washington then asked his attorney general, Edmund Randolph, whether he could make a recess appointment. On July 7, Randolph replied in a written opinion that Washington could not make an appointment because “it is now the same . . . vacancy . . . [that] existed on the 2nd of April 1792.” The vacancy did not “happen” while the Senate was in recess; “it commenced . . . on that day” of enactment.

The president’s defenders point to an opinion written by Attorney General William Wirt in 1823, which argued the opposite. Taking a loose interpretation of the Constitution — as impatient politicians are wont to do — he argued, “The substantial purpose of the constitution was to keep these offices filled; and the powers adequate to this purpose were intended to be conveyed.” Therefore, the president could make recess appointments to offices that had become vacant before the recess. Nonetheless, Wirt admitted that the strict-constructionist view was more “accordant with the letter of the constitution.”

What’s more, the president was given the recess-appointment power for a specific reason: The Senate wasn’t in session most of the year. Thus, the president needed to ensure important offices weren’t vacant for long stretches of time. Back then, intercession recesses lasted somewhere between six and nine months. Until the 20th century, in fact, Congress was in session less than half the year, on average. Nowadays, by contrast, the Senate usually recesses for somewhere between one to six weeks.

With the Senate more readily available than ever before, the president has less of an excuse for making recess appointments. Nonetheless, modern presidents have eagerly made use of Wirt’s loosey-goosey interpretation: Pres. Bill Clinton made over 130 recess appointments while in office. Bush made over 170.

The fact that Cordray’s office is new militates even further against the president’s case. The Founders generally understood a vacancy to mean, as Rappaport defines it, “an office that had previously been filled but is now empty.” In 1799, for example, Secretary of War James McHenry asked Alexander Hamilton, then serving as inspector general of the army, for his opinion on the recess-appointment power. Hamilton replied, “It is clear, that independent of the authority of a special law, the President cannot fill a vacancy which happens during a session of the Senate.” Furthermore, “vacancy is a relative term, and presupposes that the Office has been once filled.”

It’s become common practice to argue that reverting to the original understanding of the Constitution is untenable amid the complexities of modern life. But the Senate is more accessible today than it was in the 1790s. Considering the fact that recess appointments are deviations from the norm — that the Senate is in most cases supposed to approve the president’s nominees — Randolph was correct when he declared, “The Spirit of the Constitution favors the participation of the Senate in all appointments.”

Obama and all future presidents must be forced by the other branches of government, especially Congress, to respect that spirit.

— Brian Bolduc is an editorial associate for National Review.