Five months into Donald Trump’s presidency, the top ranks of the Executive Branch remain a lonely place. Commentators have, increasingly, noted the number of key positions that remain unfilled—emphasizing, in particular, critical national security roles that sit empty. For example, in April, Business Insider assessed that the Trump administration had yet to nominate candidates for 85 percent of positions requiring Senate confirmation, pointing to the concerns such absences raise for executing time-sensitive national security policies; and, in June, Vox focused on 14 vital national security positions that remained unfilled. Indeed, not only are these critical jobs empty, but there aren’t even potential officials proposed for most of them.

Several reasons have been advanced for this slow pace: a transition that made less progress selecting appointees than previous hand-offs; internal disagreements over personnel policy; and so on. Perhaps most tellingly, consistent with his professed goal of “draining the swamp,” President Trump has said that a number of the Executive Branch slots are vacant simply because he doesn’t want those roles to exist: “A lot of those jobs I don’t want to appoint because they’re unnecessary to have. We have so many people in government. . . . You don’t need all those jobs.” As Sarah Posner has noted in the Washington Post, simply failing to fill key jobs is Trump’s fastest and easiest way to deliver on Steve Bannon’s promise of the “deconstruction of the administrative state.”

And that raises an interesting and important question: Is the persistent and deliberate failure to identify candidates not merely a sign of inept governance and deadlocked politics but also, at least in certain cases, a legal failing as well?

There’s no doubt that leaving these offices empty poses real problems. Senior career officials admirably serve in an acting capacity in still-unfilled slots, but a hollowed-out political leadership makes it difficult for the U.S. Government to implement and execute policy. Appointed leaders serve as a necessary bridge between longstanding expertise and White House and departmental leadership. Presidential appointees can more credibly convey to foreign leaders the administration’s position. And when a significant crisis erupts—as one inevitably will, whether it is a natural disaster or an adversary testing us—a fully staffed team selected and trusted by the president and the Cabinet is essential to an effective response. That’s especially true when it comes to foreign policy and national security, where crises can erupt at any moment and demand authoritative, respected leadership to craft options and develop an appropriate plan of action.

For present purposes, however, let’s leave aside the policy problems raised by the large number of Executive Branch roles that remain unfilled. And let’s consider an antecedent question: Is the president legally permitted to deliberately depopulate the Executive Branch?

The Constitution’s Appointments Clause states that the president “shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors . . . and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law.” The Clause further allows Congress to forgo the advice-and-consent process with respect to the appointment of “inferior” officers.

Congress has subsequently “established” literally thousands of offices. The statutes doing so, however, are not identical: they establish offices in very different ways.

In some cases, these statutes simply authorize the president to fill certain positions. One statute states, for example, that there can be “not more than 12 Assistant Secretaries” in the Department of Homeland Security. Other statutes state that the president “may appoint” certain officials, such as an Associate Attorney General, a Chief Counsel of the Internal Revenue Service, or Deputy Administrators of the Federal Emergency Management Agency. At bottom, these statutes grant the president discretionary authority to appoint certain officers, such that not utilizing this authority may be a failure of governance or political compromise, but not the failure to perform a legal duty.

But other statutes, by contrast, are drafted quite differently. Title 10 states that “there is a Secretary of Defense . . . appointed from civilian life by the president, by and with the advice and consent of the Senate.” Similarly worded statutes establish the Deputy Secretary of Defense, many other high-level offices at the Department of Defense, and other positions across the federal government. Other statutes state that the president “shall appoint” certain officials: the Attorney General, other high-ranking Department of Justice officials, Inspectors General across the federal government, and many other critical positions.

These statutes are mandatory, not discretionary. Their language doesn’t simply permit thepresident to appoint an officer; they establish an office and require the president to fill it.

Legal scholars debate whether the Appointments Clause’s use of “shall” places an affirmative duty on the president to fill statutory offices. Noting that the Constitution uses “shall” not only to assign duties but also to allocate authority or indicate that action will be taken in the future, many scholars point to historical practice and language from early Supreme Court decisions to argue that no such constitutional duty is created.

But even if one accepts this argument, these same scholars who deny the existence of a constitutional duty recognize that “shall” is understood very differently today. Consistent with Supreme Court case law on what that word means in federal statutes, the dominant view in modern statutory interpretation is that the use of “shall” ordinarily indicates an affirmative obligation, not merely an available choice. That’s especially true in the context of these statutes. As shown above, Congress has distinguished between offices that may be filled and offices that must be filled; and, unlike certain constitutional text using “shall,” these statutory provisions serve no “predictive” purpose—to the contrary, their apparent sole function is to impose an obligation on the president to create and fill roles in the Executive Branch.

To be clear, we’re not suggesting that a new president must put forward a name to fill an empty slot at 12:01 pm on Inauguration Day, immediately after taking the oath of office. Such a rule would be consistent with neither historical practice nor common sense. The past is replete with examples of offices waiting for a nominee, often for a substantial period of time, as presidents have a lot on their plates and must spend time considering what important roles demand, identifying potential candidates, vetting their qualifications, and ultimately selecting nominees. As with a wide range of presidential obligations, the Chief Executive must therefore be given reasonable latitude to fulfill his duties in good faith and with a keen sense of the practical and feasible.

But there must be some legal limit, too. The Constitution specifically contemplates that federal offices will be “established by Law,” and there are many reasons that Congress might feel it is necessary and proper to do so. For example, the creation of an office helps ensure that certain issues receive specific attention, even if other Executive Branch officials, such as Cabinet heads, may have the authority to address those issues even in the absence of the office. The creation of an office can also ensure that the Senate has the opportunity to review the qualifications of a prospective Executive Branch official before he or she takes office. In short, Congress has a well-established and vital role to play in creating and organizing the Executive Branch that the president leads, and in so doing Congress can, as shown above, distinguish offices it believes the president has discretion to fill from those it believes he must fill. Think of the well-settled rules regarding impoundment of funds allocated by Congress: Just as the president cannot frustrate Congress’s will by unilaterally impounding funds Congress has demanded that he spend, the president also cannot, consistent with his statutory obligations, decide to override unilaterally Congress’s judgment about what Officers are necessary simply because he disagrees with that judgment or thinks a position superfluous.

Indeed, the source of this obligation goes deeper than the text of these statutes themselves. The Constitution requires the president both to “take Care that the Laws be faithfully executed” and—as Benjamin Wittes and Quinta Jurecic have noted—to swear by oath that he will “faithfully execute” the demands of his or her office. Although these provisions have long been interpreted to allow the president to exercise discretion in how he implements the law, it’s difficult to see how the president could, consistent with those provisions, reject a clear statutory command and eliminate an office simply because he disagrees with Congress’s decision to create it. That’s simply not how the constitutional separation of powers works: The administrative state, however one feels about it, was constructed by the joint efforts of Congress and the president; this means that any lawful attempt at its “deconstruction” will require the labors of both branches as well.

To be clear: This is a matter of whether to fill these positions, not with whom to fill them. There’s a long line of cases, including the famous 1926 Supreme Court decision in Myers v. United States, establishing wide latitude on the part of the president to hire and fire Executive Branch officials. The question of “whom to appoint” is, in general, a question for the president alone. But the question of “whether” is a different matter: It’s similarly long-established that Congress has an appropriate and indeed vital role to play in constructing and organizing the Executive Branch, even as that Branch’s officials ultimately report to the president. That’s what these statutes do in creating certain positions—and that’s why the president alone can choose whom to hire for them or fire from them, but not to make the deliberate choice to eliminate them by leaving them unfilled.

Now, one might ask at this point: Why does this matter? It’s not obvious that this legal issue is conducive to judicial adjudication or remedy. We haven’t conducted an exhaustive review of offices without nominees to determine all of those that the president appears legally obligated to fill. Nor are we alleging that any particular vacancy poses a legal problem. Indeed, even if we had identified such a position, any judicial challenge to the president’s inaction would likely face hurdles associated with standing to sue and the justiciability of the claims made—although it might be possible to surmount those hurdles given the right factual scenarios.

But these questions, to our mind, are secondary; they are about the redressability of the president’s illegal conduct, not about the conduct itself. Many “[c]laims concerning constitutional violations . . . cannot be addressed to the courts,” but understanding the legal nature of those issues helps all of us appreciate their significance. The first and most important point, as laid about above, is that the president’s desire to leave certain Executive Branch jobs unfilled “because they’re unnecessary” raises significant statutory and constitutional questions that shouldn’t be overlooked. If he feels otherwise—if, for example, he regards these statutes as properly read not to demand the filling of these roles, or if he views such a demand as unconstitutional—then he owes it to the American public to make explicit his understanding of the statutes and the requirements they impose on him as well as the legal reasoning behind that understanding. Without that, he’s not just failing to govern—he’s actively defying the law.