A review of existing federal laws makes clear that President Donald Trump has clear statutory authority to build a border wall pursuant to a declaration of a national emergency. Arguments to the contrary either mischaracterize or completely ignore existing federal emergency declarations and appropriations laws that delegate to the president temporary and limited authority to reprogram already appropriated funding toward the creation of a border wall between the United States and Mexico.

To analyze the legal basis for Trump’s declaration of a national emergency and subsequent transfer of existing appropriations to respond to the declared emergency, we must begin and end with the actual text of underlying federal laws governing presidential declarations and appropriations of federal funding. The most important text regarding the latter is Section 9 of Article 1 of the U.S. Constitution: “No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law[.]”

This law is what grants Congress the so-called “power of the purse” and effectively makes Congress the most powerful branch of the federal government. Not one dime may be spent by the federal government in the absence of an act of Congress. As a result, no mere declaration of emergency by the president is sufficient to allow the expenditure of funding that Congress has not already appropriated.

Much news coverage of Trump’s national emergency declaration has suggested that he is unilaterally spending money that has not been appropriated to fund construction of a wall (or fence, or security barrier, or whatever you want to call it) on the U.S. southern border, but that is simply not the case. In fact, the formal declaration of a national emergency on the U.S.-Mexico border cites two specific federal statutes that provide him the legal basis to use emergency funds to secure the border: one authorizing the president to declare national emergencies (50 U.S.C 1601 et. seq.) and the other authorizing the president to reprogram existing federal appropriations in response to an emergency declaration (10 U.S.C. 2808).

Between 2001 and 2014, according to a January 2019 analysis by the Congressional Research Service, Presidents George W. Bush and Barack Obama used those two laws in tandem 18 separate times to reprogram existing appropriations to address national emergencies, so there’s nothing unusual or unprecedented in Trump using the same authorities to respond to national security threats.

What Those Two Laws Allow Presidents to Do

But what do those two laws say about the use of presidential declarations to spend money? What kind of conditions do they require (if any), and what limitations do they place on the president? After all, as noted above, the only powers that the president can lawfully use in this instance must first be authorized by Congress.

The first law, known as the National Emergencies Act of 1976, explicitly authorizes the president to declare a national emergency. Here is the key text:

(a) With respect to Acts of Congress authorizing the exercise, during the period of a national emergency, of any special or extraordinary power, the President is authorized to declare such national emergency. Such proclamation shall immediately be transmitted to the Congress and published in the Federal Register.

(b) Any provisions of law conferring powers and authorities to be exercised during a national emergency shall be effective and remain in effect (1) only when the President (in accordance with subsection (a) of this section), specifically declares a national emergency, and (2) only in accordance with this chapter. No law enacted after September 14, 1976, shall supersede this subchapter unless it does so in specific terms, referring to this subchapter, and declaring that the new law supersedes the provisions of this subchapter.

As the text demonstrates, the president clearly has the authority to declare a national emergency. But it is important to note what is missing from the text: any conditions, requirements, or examples of what constitutes a “national emergency.” Congress put no constraints on whether a president may declare an emergency, or what conditions must be met in order for a particular event or crisis to be considered an “emergency.” Instead, the law leaves that decision solely up to the president.

Rather than constraining the president’s authority to declare an emergency, or setting conditions on what may be considered an emergency, Congress opted to limit the authority of the president to take certain actions in the event of an emergency. In other words, Congress allowed the president to walk into the room at his sole discretion, then limited what he was allowed to do in there once he entered.

The president’s authority to declare a national emergency established by statute, let us now turn to what authorities the president is granted once a national emergency is declared. Within the context of the emergency border wall debate, that law is 10 U.S.C. 2808, which delegates to the president, in the event of a national emergency that requires the U.S. military, the authority to reprogram existing appropriations for military construction projects in order to address the ongoing emergency. Here is the text of that particular statute:

(a) In the event of a declaration of war or the declaration by the President of a national emergency in accordance with the National Emergencies Act (50 U.S.C. 1601 et seq.) that requires use of the armed forces, the Secretary of Defense, without regard to any other provision of law, may undertake military construction projects, and may authorize the Secretaries of the military departments to undertake military construction projects, not otherwise authorized by law that are necessary to support such use of the armed forces. Such projects may be undertaken only within the total amount of funds that have been appropriated for military construction, including funds appropriated for family housing, that have not been obligated.

(b) When a decision is made to undertake military construction projects authorized by this section, the Secretary of Defense shall notify, in an electronic medium pursuant to section 480 of this title, the appropriate committees of Congress of the decision and of the estimated cost of the construction projects, including the cost of any real estate action pertaining to those construction projects.

(c) The authority described in subsection (a) shall terminate with respect to any war or national emergency at the end of the war or national emergency.

There are several important phrases in this particular statute, namely “requires the use of the armed forces,” “military construction projects,” and “necessary to support such use of the armed forces.”

Who determines whether the use of the armed forces is required during a particular national emergency? The simple answer is that such discretion belongs to the president of the United States in the discharge of his duties as commander-in-chief. As Article II of the U.S. Constitution states, “The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States[.]”

In the absence of federal laws prohibiting the deployment or use of the armed forces (e.g., the Posse Comitatus act prohibits the Army and Navy from engaging in domestic law enforcement), the president’s discretion on whether use of the armed forces is required to secure and defend the United States is absolute.

Similar to the law authorizing the president to declare a national emergency, nowhere in the statute at issue does Congress set forth certain conditions that must be met prior to determining that the use of the U.S. military is required. As a result, that authority belongs to the president. The authority to make that determination does not reside with professional political pundits, party activists, or even federal judges. Under the U.S. Constitution, it is the president and no one else who retains the authority to command the U.S. military.

Is a Border Wall a Military Construction Project?

Thus far we have established that the president has the legal authority to 1) declare a national emergency, and 2) determine that the U.S. military is required to respond to such an emergency. The above statute, 10 U.S.C. 2808, states that the president may reprogram existing appropriations towards “military construction projects” if he has declared a national emergency that requires the use of the armed forces.

Does a barrier to protect the U.S. border and those who reside within it qualify? To determine that, we must examine the law’s definition of “military construction projects.” Here is how that law defines the term:

(a) The term ‘military construction’ as used in this chapter or any other provision of law includes any construction, development, conversion, or extension of any kind carried out with respect to a military installation, whether to satisfy temporary or permanent requirements, or any acquisition of land or construction of a defense access road (as described in section 210 of title 23).

Given that definition, we must now examine how the law defines the term “military installation”:

(4) The term ‘military installation’ means a base, camp, post, station, yard, center, or other activity under the jurisdiction of the Secretary of a military department or, in the case of an activity in a foreign country, under the operational control of the Secretary of a military department or the Secretary of Defense, without regard to the duration of operational control.

Per those statutes, a military construction project is “any construction…with respect to…activity under the jurisdiction of the Secretary of a military department.”

The border wall clearly qualifies as “construction,” so that portion of the statute is satisfied, but does it qualify as “activity under the jurisdiction of the Secretary of a military department?” Some legal commentators assert that the answer is “no,” since immigration enforcement and border security generally fall under the jurisdiction of the Department of Homeland Security.

As a broad matter, that seems to be a difficult position to hold, given that it requires one to argue that the military has no role in protecting the United States. If border security is solely the matter of non-military agencies, then it must follow that the U.S. military would have no role, authority, or jurisdiction in repelling an invasion of the United States, a position that is clearly nonsensical.

Similarly, it makes little sense to argue that two presidents were justified in using emergency authority to reprogram funds to build and maintain U.S. facilities in foreign nations in order to protect their security, as they did 18 separate times between 2001 and 2014, but that the current president has no authority to use the same funds to secure actual American soil from foreign invasion.

DHS Has Asked the U.S. Military to Help Secure the Border

But even as a narrow matter within the confines of the underlying statutes at issue, the argument that a border wall does not qualify as “any construction…with respect to…activity under the jurisdiction of the Secretary of a military department” also fails.

That’s because the military clearly has jurisdiction in the area given multiple formal requests by the Department of Homeland Security (DHS) to assist that agency not in its law enforcement or immigration processing activities, but in its requirement to secure the U.S. border via the Secure Fence Act of 2006 (Public Law 109-367). That law requires the DHS secretary to “take all actions the Secretary determines necessary and appropriate to achieve and maintain operational control over the entire international land and maritime borders of the United States, to include…physical infrastructure enhancements to prevent unlawful entry by aliens into the United States[.]”

The DHS secretary has repeatedly over the last several months requested the formal assistance of the U.S. military to secure the border.

That law further defined “operational control” of the border as the “prevention of all unlawful entries into the United States, including entries by terrorists, other unlawful aliens, instruments of terrorism, narcotics, and other contraband.”

Pursuant to that statutory requirement to secure the border and prevent “all unlawful entries into the United States,” the DHS secretary has repeatedly over the last several months requested the formal assistance of the U.S. military to secure the border. Last October, the secretary of defense formally accepted the request for assistance from DHS.

“After receiving a request for assistance from the Secretary of Homeland Security, the Secretary of Defense has approved providing mission-enhancing capabilities to Department of Homeland Security, U.S. Customs and Border Protection (CBP) along the Southwest Border (SWB). This assistance is in addition to the previously authorized support to CBP’s Operation Guardian Support mission,” a joint statement from both agencies declared.

Given that the U.S. Congress passed a law requiring a secure border, the DHS secretary asked for military assistance to achieve that statutory mandate, the secretary of defense agreed and deployed forces in support of that mission, and that the military has been actively working to achieve that mission, it appears beyond debate that border barrier construction by the military in this particular area clearly satisfies the statutory definition of “any construction…with respect to…activity under the jurisdiction of the Secretary of a military department.”

The President Could Also Use These Funds

Although not referenced specifically by the president, an additional law (33 U.S.C. 2293) gives the president the authority to reprogram certain civil defense funds, namely appropriations for the U.S. Army Corps of Engineers, to support the federal response to a declaration of national emergency:

(a) Termination or deferment of civil works projects; application of resources to national defense projects

In the event of a declaration of war or a declaration by the President of a national emergency in accordance with the National Emergencies Act [50 U.S.C. 1601 et seq.] that requires or may require use of the Armed Forces, the Secretary, without regard to any other provision of law, may (1) terminate or defer the construction, operation, maintenance, or repair of any Department of the Army civil works project that he deems not essential to the national defense, and (2) apply the resources of the Department of the Army’s civil works program, including funds, personnel, and equipment, to construct or assist in the construction, operation, maintenance, and repair of authorized civil works, military construction, and civil defense projects that are essential to the national defense.

That law allows the president, pursuant to a declaration of a national emergency that requires the use of the armed forces, to reprogram funding for nearly all Army civil works projects towards the construction of a border wall.

Many commentators who have expounded on the legality of Trump’s decision have declared, without any statutory basis, that there is simply no border emergency, therefore everything Trump is doing on the matter is illegal. Some claim that the emergency does not require the use of a wall. Others claim that a wall does not constitute a military construction project. As demonstrated above, the plain text of the underlying statutes requires a neutral arbiter to reject these legal claims in their entirety.

The president has the authority to declare a national emergency, to determine whether use of the armed forces is required to respond to it, and to use already appropriated funds for military construction or civil defense construction funds to respond to the declared emergency. Current federal law requires a secure border, and empowers the Department of Homeland Security to use any means necessary to prevent all unlawful entries across the border. The Department of Homeland Security formally requested the assistance of the U.S. military, and the Department of Defense agreed to support the mission of securing the U.S. border. These activities happened not just within the confines of existing federal law, but because of it.

All This Doesn’t Mean It Was a Smart Move

As a legal matter, Trump’s authority to declare a national emergency on the border then reprogram a limited amount of existing military construction or civil defense project appropriations to address the emergency is well-established. Whether it is wise to do so as a political matter is an entirely different question. The question of “should” is entirely different than the question of “can.” And there many valid political arguments on both sides of the debate.

There are also valid arguments that the congressional delegations of power to the president may themselves be unconstitutional, but one wonders why those arguments were never raised when previous presidents repeatedly used these same powers. Unfortunately, many pundits have deliberately conflated the “can” and the “should” and used rhetorical subterfuge to do so. Some oppose the end result — Trump using certain Department of Defense funds to build a wall to secure the border — yet pretend that it is the process, one that is entirely legal and precedented, that bothers them.

Trump is operating within the bounds of a clearly defined and narrow delegation of authority within the realm of appropriations law.

Others have claimed that if Trump can use a declaration to build the wall, then a future left-wing president could use an emergency declaration to seize guns or levy massive taxes on families and businesses to stop global warming. While future presidents may rhetorically cite Trump’s use of an emergency to justify their own power grabs, such rhetoric comes with no legal authority, which is the only thing that matters in these particular situations.

Trump is operating within the bounds of a clearly defined and narrow delegation of authority within the realm of appropriations law. He has not conjured funding from thin air (the military construction and Army Corps funding has already been appropriated), nor is he using funds for purposes explicitly prohibited by Congress (to the contrary, Congress explicitly authorized the construction of a border wall). A president who attempted to unilaterally levy taxes or confiscate lawfully owned property pursuant to some declaration would not be operating within the law, and Trump’s use of limited appropriations transfer authority will have no legal bearing on potential attempts by future presidents to exercise presidential authority outside the bounds of the law.

With all that said, the entire legal debate is almost academic at this point, as courts have repeatedly assumed for themselves authority that they do not have to prohibit Trump from exercising authority that clearly belongs to him. Regardless of what the law actually says, and how previous presidents have previously used it, a federal district court judge in Hawaii or California is surely champing at the bit for an opportunity to issue a nationwide injunction against Trump’s latest move under the legal doctrine of Orange Man Bad.