In his most radical effort yet to frustrate efforts by desperate people to seek refuge in the United States, President Trump is hoping to put in place a new regulation that would basically put an end to asylum-seeking along at the southern border.

But just like many other Trump efforts, this one looks particularly vulnerable to legal challenge, and the American Civil Liberties Union filed a lawsuit on Tuesday to block the regulation.

The argument that the ACLU is making cuts to the core of the folly of Trump’s whole agenda when it comes to asylum seekers, in a way that goes beyond the legal details.

During an interview, Lee Gelernt, the deputy director of the ACLU’s Immigrants’ Rights Project, told me the lawsuit argues that Trump’s new rule clearly flouts the intent of Congress as expressed in the Immigration and Nationality Act (INA), which set up key aspects of today’s asylum law regime.

The new administration rule would render migrants ineligible for asylum if they do not apply for (and get denied) asylum in one of the countries they pass through en route to the United States. But under current federal law, any person on U.S. soil — including undocumented immigrants, whether they just crossed the border or were detained in the interior — who requests asylum or expresses a fear of persecution if returned to a home country must be given an asylum interview.

So the administration is arguing that the INA also gives the attorney general and the Homeland Security secretary the discretion to set “conditions or limitations” that would render asylum seekers ineligible for it. In this case, the condition is that they must apply for — and be denied — application in another country through which they pass.

Given that most asylum seekers now come from Central America, this would severely curtail asylum requests along the U.S.-Mexico border As Michael D. Shear and Zolan Kanno-Youngs point out for the New York Times, it would mean Hondurans and Salvadorans must apply in either Guatemala or Mexico, and Guatemalans would have to apply in Mexico — and be denied — which would “stop virtually all Central American families who are fleeing persecution and poverty from entering the United States.”

But the INA also requires that any such conditions placed on asylum eligibility must also be consistent with the statute, and here is where the ACLU sees a vulnerability.

As Gelernt tells me, the INA expressly points to only two scenarios under which asylum can be denied on the basis of having passed through another country. The first is when the United States has entered into a “safe third country” agreement with that country; the second is when the asylum seeker has already firmly resettled in that country.

Neither of these scenarios would apply to the vast majority of those who would be denied asylum under the new administration rule, Gelernt points out.

This has some important parallels in another failed effort to restrict asylum. The administration recently tried to deny asylum to anyone who crosses the border between official ports of entry, citing the same discretion to set “conditions.”

But the courts blocked the move, noting that the INA expressly says asylum seekers can apply no matter where they enter the country. (It’s now being litigated on the merits.) In this case, the administration tried to evade Congress’ intent in preventing such a denial — asylum seekers are often fleeing horrific conditions and can’t plan exactly where they enter — and was stopped.

It’s not yet clear whether the current battle will be quite as clear cut. But what’s particularly interesting here is the larger issues to which this points.

Gelernt notes that the fact that Congress expressly set conditions under which asylum might be restricted against those crossing through other countries means Congress deliberated over whether that might be an appropriate basis for denying it, and decided it wasn’t.

“Congress has thought about this issue, and decided that transiting through another country is not a sufficient basis to render somebody ineligible for asylum,” Gelernt told me.

Notably, the two conditions under which the INA justifies denying asylum based on crossing through another country — a third-country agreement, or a migrant being firmly resettled — are both conditions that would generally require more cooperation between the United States and other countries.

But Trump has moved directly in the opposite direction, moving to cut off aid to Central American countries, even though that aid would address many of the root causes of migrations. At the same time, the administration is doing everything it can to choke off ways of applying for refuge here, and making regional diplomacy as a means for refugee sharing less likely.

Thus, Congress contemplated more regional cooperation as one route to creating the exceptions to asylum eligibility that Trump is now claiming. So in a sense, the vulnerability of the latest lawsuit points to the folly of the administration’s broader approach.

And that approach has now veered in a truly radical direction.

“This is the most extreme measure they’ve taken,” Gelernt said. “This would effectively eliminate asylum at the southern border.” Hopefully, it won’t last.

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