Donald Trump has signed a new government funding and border security bill after it was voted through by the Senate and House of Representatives, averting a second shutdown.
But the deal thrashed out by bipartisan negotiators awards the president just under $1.4bn (£1.1bn) in federal funding for his proposed Mexico border wall, well short of the $5.7bn (£4.4bn) he originally demanded and only enough to buy 55 miles of the 2,000-mile barrier he envisions towering from the Pacific to the Gulf of Mexico.
Speaking from the White House Rose Garden, the president declared the illegal immigration crisis on the US’s southwestern border to constitute a national emergency, empowering him to bypass Congress and apportion the funds he needs from other federal programmes.
But what exactly does it mean to make such a declaration?
The National Emergencies Act, passed in 1976 under Gerald Ford, empowers the president to take executive actions without congressional oversight (but within legal bounds) in the event of a crisis. The measure effectively relieves him of many of the checks on his authority at his own instigation, a state of play condemned by legal scholars.
Of particular interest to President Trump will be his newfound freedom to control military construction initiatives.
Precisely what constitutes a national emergency is vague. George W Bush declared one in the aftermath of 9/11, for instance, when the US believed the possibility of further Islamist terror attacks represented a clear and present danger. But there is no legal definition in place, no ratification by Congress and no judicial review.
Senior Democrats Nancy Pelosi and Chuck Schumer were quick to denounce President Trump’s plan to employ the measure when it was first revealed by Senate majority leader Mitch McConnell on Thursday, arguing the problem of gun violence is a far greater cause for concern than impoverished asylum seekers from Central America.
“Declaring a national emergency would be a lawless act, a gross abuse of the power of the presidency and a desperate attempt to distract from the fact that Donald Trump broke his core promise to have Mexico pay for his wall,” Speaker Pelosi tweeted.
“Absolutely it’s an abuse of power for the president to declare a national emergency when none exists and to use it to try to get around the democratic process,” agrees Elizabeth Goitein, co-director of the Liberty and National Security Programme at the Brennan Centre for Justice, who warned of the need to redfine the measure in The Atlantic in December 2018.
“We are in a situation where our legal system for emergency powers almost invites that kind of abuse.”
In the past, emergencies have typically been declared relating to foreign affairs or containing conflicts overseas.
Mr Trump's predecessor, Barack Obama, declared 13 emergencies during his eight-year tenure in the White House and President Trump has declared three previously: one on global human rights abuses, one on penalising violence in Nicaragua and one regarding foreign intervention in American elections.
To declare one on the Mexican border on the basis of illegal immigration, when most people residing illegally in the US are there because they have overstayed the terms of their visas rather than because they trespassed across the line on foot, is certainly unorthodox and expected to provoke a legal challenge from the Democrats.
The opposition could also veto the national emergency declaration on the grounds that the act contains a clause allowing Congress to do so if both the House of Representatives and the Senate vote for it, although this has never previously been attempted.
The former is controlled by the Democrats since November’s midterms, but the Republicans hold on to the Senate. However, Mr Trump’s party are by no means united on the need for a wall.
In the meantime, all eyes will be on how Mr Trump uses his powers to rake together the money for his wall.
According to CNN, he will supplement the $1.4bn (£1.1bn) granted by the new bill with $600m (£468m) from the Treasury Department's drug forfeiture fund, $2.5bn (£1.9bn) from the Defence Department's drug interdiction programme and $3.5bn (£2.7bn) from its military construction budget.
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