Donald Trump managed to score a big win against illegal immigration without Congress’ help. Can he win another on his own? Rather than flexing economic power with Mexico to gain tougher enforcement against illegal immigration, this time Trump will act on his own to remove the incentives for it. A new rule entered in the federal register will deny most asylum applications from Central America regardless of circumstance by imposing a de facto “safe third country” requirement:

The Trump administration is preparing a new rule that would dramatically limit the ability of refugees to seek asylum at the U.S. border with Mexico.

Under the rule, released online today, with limited exceptions refugees seeking asylum would have to do so in a third country through which they transited, rather than at the U.S. border.

“Ultimately, today’s action will reduce the overwhelming burdens on our domestic system caused by asylum-seekers failing to seek urgent protection in the first available country, economic migrants lacking a legitimate fear of persecution, and the transnational criminal organizations, traffickers, and smugglers exploiting our system for profits,” Kevin McAleenan, the acting secretary of the Department of Homeland Security, said in a statement.

Attorney General William Barr highlighted this change as a bulwark against fraud. Barr’s likely honing a legal argument that he will have to deliver in court soon:

Attorney General William Barr insisted the new rule will “decrease forum shopping by economic migrants and those who seek to exploit our asylum system to obtain entry to the United States—while ensuring that no one is removed from the United States who is more likely than not to be tortured or persecuted on account of a protected ground.”

On its face, the change is long overdue and returns the policy of asylum to its original intent. Asylum claims are supposed to deal with oppression by totalitarian and genocidal governments, not just a degraded economic and police environment. Normal immigration suffices for those conditions, and the United States provides for a regulated legal process for applications to emigrate for all others. The US is relatively generous when it comes to legal immigration, and we could afford to be even more generous if we ever clamp down on illegal immigration.

In the absence of Congress, or what has really been an abdication by Congress, the Trump administration is making a logical choice to remove the incentives for illegal immigration. First they forced Mexico to act responsibly in securing its own southern border and curtailing the trafficking of illegal immigrants through their country, a move long overdue. Now they want to end the draw for the caravans — the asylum policy and practices that makes border enforcement a sieve.

But will it work without congressional action? Needless to say, a rational lawmaking process to reform immigration laws is much more preferable than EOs for all sorts of reasons, the first being that the policy would be better prepared against legal action. The Associated Press outlines the legal fight ahead for the Trump administration:

The policy is almost certain to face a legal challenge. U.S. law allows refugees to request asylum when they arrive at the U.S. regardless of how they did so, but there is an exception for those who have come through a country considered to be “safe.” But the Immigration and Nationality Act, which governs asylum law, is vague on how a country is determined “safe”; it says “pursuant to a bilateral or multilateral agreement.”

Right now, the U.S. has such an agreement, known as a “safe third country,” only with Canada. Under a recent agreement with Mexico, Central American countries were considering a regional compact on the issue, but nothing has been decided. Guatemalan officials were expected in Washington on Monday, but apparently a meeting between Trump and Guatemalan President Jimmy Morales was canceled amid a court challenge in Guatemala over whether the country could agree to a safe third with the U.S.

The new rule also will apply to the initial asylum screening, known as a “credible fear” interview, at which migrants must prove they have credible fears of returning to their home country. It applies to migrants who are arriving to the U.S., not those who are already in the country.

Federal judges have not been as kind to Trump’s unilateral acts on immigration as they were to Barack Obama’s. Given the murky language of the Immigration and Nationality Act, courts may well find that Trump has some leeway to define the policy in this manner, but they’re more likely to issue temporary injunctions against it and engage in lengthy trials to discuss the issue. It might take months before the appellate circuits set any kind of precedent, and it’s a good possibility that those will conflict, requiring the Supreme Court to settle the issue. Donald Trump would have to win another term in office to press the case that far, and it might be that long before such a policy could be enforced outside of congressional action to codify asylum more specifically.

Still, this ratchets up the pressure in two different ways. First, it’s likely to discourage the free-for-all run at the border that we saw earlier this year as asylum looks like an even worse bet for migrants than it did before. Second, it will shift attention on Congress to get something done on immigration reform. Incentivizing Presidents Pen-and-Phone by inaction is eroding Congress’ ability and legitimacy to govern, and even a compromise on immigration might not be the worst of all worlds for future Congresses — or even this one.