Then-attorney general nominee William P. Barr speaks during a hearing before the Senate Judiciary Committee on Jan. 15. (Bonnie Jo Mount/The Washington Post)

IN ITS tireless efforts to tighten the vise on Central American asylum seekers, the Trump administration has settled on a new tactic: indefinite detentions likely to last months or years, even for some migrants initially judged to have a credible fear of persecution in their home countries. The order, which represents Attorney General William P. Barr’s first foray into immigration policy since he was confirmed in February, overturns long-standing precedent and suggests he is in lockstep with the White House’s no-holds-barred approach.

Mr. Barr’s order is limited — it applies neither to unaccompanied minors nor to families with children, each of which can be held no more than 20 days if they clear the initial “credible fear” screening, under a 22-year-old court order. Nor would it affect asylum seekers who cross at any of the dozens of legal ports of entry along the southwestern border. Those two groups represent a large majority of the tens of thousands of asylum seekers now crossing into the country monthly.

Still, more than 20,000 other migrants were apprehended in January crossing between legal entry ports, and many of them declared their intent to seek asylum. If Mr. Barr’s order, which forbids those migrants from seeking release on bond, is implemented — he put it on hold for 90 days, and it faces court challenges in the interim — they could be warehoused for months or years pending adjudication of their asylum claims.

Given the flood of migrants seeking to cross into the United States, it’s fair for the administration to discourage Central Americans from setting off on a dangerous journey that for most will end in a deportation order. Faced with a similar migrant surge in 2014, the Obama administration also sought various means of deterrence.

The trouble with Mr. Barr’s order is that it blurs theory and practice. In theory, it would be reasonable to detain migrants at the border — provided there were adequate and suitable detention facilities at which migrants could be held in humane conditions to wait days or a few weeks while their cases were adjudicated by immigration judges with manageable caseloads. In practice, detention centers run by Immigration and Customs Enforcement are holding a record 50,000 migrants, more than Congress has authorized. Those facilities are over capacity. In the meantime, some 400 immigration court judges face a backlog of well over 800,000 cases, meaning that new cases are routinely scheduled for 2021 and beyond.

Mr. Barr’s order is the latest example of President Trump’s preference for punitive rather than pragmatic policy. Instead of hiring hundreds more immigration judges to expedite adjudication and reduce caseloads, the administration forces some migrants back into Mexico while they await the outcome of asylum applications, and slow-walks the processing of asylum seekers at ports of entry, prompting some to seek illegal entry in remote areas. The president complains about “catch and release” but is loath to strike a deal with Congress that would trade protections for the “dreamers,” for instance, for adequate resources for enforcement. Mr. Trump’s latest pronouncements on immigration — “I’m not playing games” — make great sound bites but do little to resolve what has become a bona fide crisis.