The administration has been trying to figure out how exactly to try to implement the president’s executive order. The issue isn’t zero tolerance in general — that will remain and there may be ramped up prosecutions of single adults at the border. The question is what to do about families. Counter to what Customs and Border Protection suggested last week, the administration will still seek to prosecute adults with children.

The model will now be holding adults and children together in DHS facilities, and fashioning some system involving DHS and the U.S. Marshalls to take the adults to court and then return them to the DHS facilities. The administration will also do everything it can to expedite the asylum process, perhaps having judges work through claims on site at the DHS facilities or other expedients.

This is a sensible framework, but we have seen over the last couple of weeks the difference between writing a policy on paper and implementing it (the Wall Street Journal has a good story today on the insane bureaucratic obstacles one family encountered trying to get an eight-year-old back after a separation). The practical problem with the new policy is, of course, limited capacity and limited legal authority. My understanding is that DHS currently has three family facilities — two in Texas and one in Pennsylvania. It will try to come up with more space quickly to the extent it can, but this isn’t easy (and re-purposing military space may require congressional action). Plus, the Flores Consent decree remains in place. Absent relief from the Ninth Circuit or legislation from Congress, after 20 days the administration will have to decide whether to release children and parents together or release children separately. After the uproar of the last couple of weeks, it’s hard to see how separations in any form will be defensible.

The upshot is that the administration has a conception of what it wants to do (and a much better one than its abandoned policy), but only a skeleton of the infrastructure it would need to carry it out, and insufficient legal authority. All the factors that have made it impossible for the U.S. to respond effectively to the migrant crisis remain in place and will surely defeat this latest initiative unless Congress acts.