The Trump administration bragged, and not for the first time, about its crackdown on unauthorized immigrants living in the US on Tuesday — hyping a 27.8 percent increase over last year in removal orders issued from February to June.

Also on Tuesday, new statistics from the Department of Homeland Security (reported by Politico’s Ted Hesson) showed that deportations are actually down from last year — from an average 20,000 deportations per month in 2016 to an average of 16,900 over the first five months of Trump’s presidency.

Why the discrepancy?

The (relatively) slow pace of deportations since Trump came into office is partly because of something Trump’s been bragging about: the decline in people crossing into the US from Mexico without papers. And it’s partly because the deportation system simply isn’t built for speedy deportations of people who’ve lived in the US for years. In fact, it’s backlogged to the point of near-paralysis.

The new stats show that the existing system is going to be a huge obstacle to the stepped-up deportations Trump and his administration clearly want — unless they work to streamline it by giving fewer chances to fewer immigrants in court.

The Trump administration has definitely gotten more aggressive in putting people into the deportation system. That hasn’t immediately resulted — because it couldn’t — in getting people out of the country. They’re blowing a little statistical smoke to obscure the latter, but the former shouldn’t be overlooked either.

Trump is arresting more people in the US — but can’t deport them quickly

When someone living in the US is taken into custody by federal immigration agents for the first time, they can’t just be deported without their consent. They have to go through a hearing in immigration court to establish that they’re “deportable” (i.e., that they don’t have or have violated their legal status), and that they’re not eligible for forms of “relief” from deportation like asylum.

Mexican immigrants caught crossing the border aren’t entitled to those protections. As a result, many of the deportations the government actually reports in a given month aren’t of longtime residents of the US, but “border apprehensions.”

Border apprehensions plummeted at the beginning of the Trump presidency. They’re creeping up now, but they’re still below the levels of the past few years — which were, themselves, way lower than the levels of border-crossers in the early years of the 21st century.

The Trump administration loves to brag about this as proof that it’s “secured the border.” But one consequence is that a ready pool of available deportees just isn’t available to them.

So the decrease in deportations, compared to Obama levels, is explained by border crossing decline. But that decrease is happening despite stepped-up enforcement against unauthorized immigrants living in the US — and that’s because of the backlog in immigration court.

According to Immigration and Customs Enforcement data, ICE arrests of immigrants have gone up from an average of 9,134 per month (October to December 2016) to 13,085 a month during February to June 2017.

Some of its targets — people who were previously deported or ordered deported, for example — can be deported again without going through immigration court. But there’s only so much low-hanging fruit out there.

According to data collected by the Transactional Records Access Clearinghouse, the Trump administration opened deportation cases against about 25 percent more people this year than the Obama administration did in the first six months of 2016 (about 145,000 this year versus about 107.000 last year). But they’re just stuffing more and more cases into a very narrow and backlogged tube.

The immigration court backlog is the biggest obstacle to Trump’s border and deportation agenda

Under the Bush and Obama administrations, the agencies responsible for immigration enforcement (under the Department of Homeland Security) got a bunch more money to apprehend and deport a bunch more immigrants. But the agency in charge of immigration courts, under the Department of Justice, didn’t get the same kind of funding boost to process those cases.

As a result, the time to resolve a case in immigration court is often measured in years. From October 2016 to June 2017, someone who got an official removal order from an immigration court judge had started the court process 378 days earlier. And the average case still pending in immigration court, as of June, has been pending for 667 days — the equivalent of 19 months. (Some of the states with the biggest populations of unauthorized immigrants have even longer backlogs; the average case in immigration court in New York has been pending for 852 days, or two years and four months.)

In other words, the people the Trump administration has deported in its first five months aren’t mostly people it arrested. They’re mostly people arrested under the Obama administration.

Furthermore, even arrests at the border can often exacerbate the court backlog.

A lot of the cases immigration judges are hearing are from Central American families seeking asylum — people who were apprehended crossing the border over the past few years, but weren’t deported immediately because they weren’t from Mexico and had asylum claims.

This is the real reason the Trump administration has been able to issue more removal orders this year: Many of those Central American families have stopped showing up to court out of fear they’ll be deported if they lose their cases. According to a Marshall Project report by Julia Preston in July, 70 percent of Central American families’ cases are resulting in deportation orders issued “in absentia” — with the immigrants themselves somewhere ICE hasn’t found them.

The fact that those families can’t be deported quickly is an object of some consternation to immigration hawks, who worry — not without cause — that more Central Americans will be inspired to flee their countries for the US if they know that their relatives or neighbors aren’t being sent right back. And some Border Patrol agents are worried that a new wave of immigrants might be coming into the US in fall, now that they’re no longer afraid of what the administration will do.

So the immigration court backlog doesn’t just threaten Trump’s deportation plans. It threatens his much-trumpeted “improvements” to border security.

Congress could turn its attention to immigration court — or the administration could streamline it at the cost of due process

The easiest way to solve a capacity problem is to hire more people, and the federal government has tried to do that with immigration court: 25 new judges (hired under the Obama administration) have started in the past year. But the number of new cases the Trump administration has filed, and its reluctance to close cases and let immigrants go, means that the backlog has grown faster than the capacity.

Putting a serious dent in the backlog would require hiring dozens more judges. That’s money. And that money would have to go to the Executive Office of Immigration Review in the Department of Justice — not an agency that immigration hawks in Congress typically have their eye on as a key funding priority.

Without more money from Congress, the administration’s only options are to try to make cases go faster or to try to find more ways to deport people without putting them into court.

They’re trying to pressure immigration judges to do the former. A strongly worded memo sent out to immigration judges in July told them to be strict about granting “continuances” (agreements to postpone resolving the case until a new hearing can be scheduled, so that immigrants can get their cases in order) so that it didn’t take as many hearings to resolve a case. But they can’t dictate exactly what immigration judges do.

It would be much simpler, and much more efficient, to make it easier to deport people without court hearings — by expanding the process currently used for Mexican border-crossers to apply to other immigrants as well. That can be done by rewriting the regulations that determine who qualifies for “expedited removal.”

Currently, immigrants caught within 100 miles of the border can be “expedited” out of the US unless they can prove that they’ve been in the US for at least two weeks. But the administration is allowed to expand that to cover immigrants caught anywhere in the country — and to force immigrants to prove two years of residence in the US to be allowed to stay.

The executive orders signed by President Trump in January opened the door to such an expansion, but the Department of Homeland Security hasn’t announced any plans to change the regulations. It’s possible that DHS will only moderately expand the use of expedited removal. But it’s also possible that the Trump administration will get so fed up with the roadblock that immigration courts present to its deportation agenda that it will do everything it can to avoid the courts entirely.