Once a family requesting asylum is in our legal system, and awaiting a hearing, if they have a minor with them, the child cannot be held in custody for longer than 20 days. And — thankfully — now that Trump has reversed his “zero tolerance” policy, parents and children cannot be separated unless the parent is deemed to pose a danger to a child. (Even this is controversial, though, as the standards of parental behavior are not sharply defined, and because thousands of children separated under Trump’s original policy still have not been accounted for.)

In any event, today if a family can pass the credible-fear interview, the whole family has to be released inside America within 20 days while waiting to see an immigration judge, which can take two or three years because of the backlog. So they fade into America. Studies show that a majority show up for their hearings, but tens of thousands have not.

As I said, many of these families do meet the standards for asylum; others are looking for work. One reason many asylum seekers enter illegally, though, is that at official entry points they are told by border agents that limited staffing precludes more than a small number of asylum applications from being processed each day, so the immigrants need to wait in Mexico. But as a result of this crush of applications, more and more people who really have had to flee persecution get pushed further and further back in line for a hearing.

The Customs and Border Protection headquarters in San Ysidro has temporary holding rooms for 300 people, be they asylum seekers, illegal migrants caught somewhere on the border that we need to repatriate or drug smugglers destined for prosecution. Everyone gets a health check and an interview to determine what legal track to be put on.