OCTAVIO NAVA CABRERA was pulled over by police in Illinois in April 2013 for going through a stop sign. He had arrived in the state in 1986, aged 13, and most of his family still live there. He did not have a proper driving licence and had an immigration violation dating from 1997, when he was stopped at the border after a trip to Mexico. Mr Nava Cabrera was imprisoned for seven months and then deported, leaving a son behind. He is now sleeping on the floor of a friend’s apartment in Mexico City and slightly baffled by the whole experience. “I don’t know anything about Mexico,” he says.

America is expelling illegal immigrants at nine times the rate of 20 years ago (see article); nearly 2m so far under Barack Obama, easily outpacing any previous president. Border patrol agents no longer just patrol the border; they scour the country for illegals to eject. The deportation machine costs more than all other areas of federal criminal law-enforcement combined. It tears families apart and impoverishes America.

The strongest economic arguments in favour of a more liberal immigration policy are techies like Satya Nadella, Microsoft’s new Indian-born boss. Half of those who earn science and technology PhDs at American universities are foreign-born, as are the authors or co-authors of four-fifths of drug patents. America’s reluctance to allow foreign graduates to stay in the country when they finish college will reduce its chances of bagging future Mr Nadellas. Yet the unskilled immigrants who are being shipped back to Mexico enrich America too. They work, pay taxes and fill niches that the native-born shun. Farms, hotels and restaurants depend on them; so do professional couples who need someone to hold the children while Dad writes code and Mum drills teeth.

Why would a supposedly liberal president oversee something so illiberal, cruel and pointless? The Machiavellian explanation is that it motivates Latinos, who associate such barbarism with Republicans, to keep voting for the Democrats. Mr Obama’s defenders prefer two other excuses.

First, he is merely following laws written by nativist Republicans. This is a cop-out. As president he sets priorities for the executive branch, which cannot catch and prosecute everyone who breaks any of the gazillions of federal rules. He can find ways to slow the deportation of harmless immigrants and concentrate on those who have committed serious crimes. He has already delayed action against those who arrived as children.

More visas, fewer expulsions

The second excuse is that this is all part of Mr Obama’s grand strategy to secure immigration reform this year, including a path to legal status for the 12m illegal immigrants now in the country. There is room for a deal (see article). The House Republicans have long believed that letting in more people like Mr Nadella is a good thing, and they are inching towards some sort of amnesty process for undocumented workers like Mr Cabrera. They still dislike the idea of illegal immigrants becoming citizens (and voting for Democrats), while the Democrats are suspicious of temporary-worker schemes. These differences would be bridgeable, with a little trust. Given its absence, Mr Obama will only win Republican votes by showing that the border is secure.

Immigration reform is indeed a great prize. But die-hard nativists are unlikely to be swayed, no matter how tough the laws, and reform can pass without their votes. There are very few things about America that are as vindictive and self-defeating as its deportation machine. Rather than making excuses for keeping it, Mr Obama should be exposing its awfulness and leading the campaign to de-fang it.