NEAR the end of his bewildering ordeal in Franz Kafka’s “The Trial”, Josef K. gets some advice from one Titorelli, the court artist. So-called "actual acquittals" are the stuff of legend, Titorelli tells K. More realistic options are “protraction” (keeping one’s case simmering forever) or “apparent acquittal”—release with a looming possibility of re-arrest and re-trial at an unspecified future point. The follow-up brush with the law could happen years later, as soon as the poor soul arrives home or any time in between. The court “forgets nothing”. Whenever the authorities renew their charges against the released defendant, Kafka writes, “his life as a free man is at an end."

American law imitated Kafka’s fiction on March 19th when a 5-4 Supreme Court majority ruled that many immigrants who had been held in criminal custody are subject to mandatory detention by Immigration and Control Enforcement (ICE) at any time after their release. Eduardo Vega Padilla, one of the litigants in Nielsen v Preap, came to America in the 1960s as an infant and soon became a lawful permanent resident. In the late 1990s, he was twice convicted for possessing drugs and, in 2002, for illegally owning a firearm as a prior felon. In 2013, 11 years after finishing his six-month sentence for the gun conviction—now a father of five and grandfather of six American citizens—Mr Padilla answered a knock at his door and was taken into custody by immigration officials. He found himself on the cusp of being deported to Mexico, a country he left when he was 16 months old.

The question the justices tackled in Preap was how to interpret a 1996 law—the Illegal Immigration Reform and Immigrant Responsibility Act—requiring the detention of immigrants “when the alien is released” following offences ranging from serious felonies to drug possession or “moral turpitude” misdemeanours like jumping a turnstile or illegally downloading music. The Ninth Circuit Court of Appeals ruled in 2016 that green-card holders may not be nabbed and held indefinitely without a bail hearing long after being released from criminal custody. The law, the appeals court said, permitted ICE to swoop in only at the time of the immigrant’s release. If authorities wanted to detain an alien at a later time, they’d have to give him a hearing where he could try to prove he neither posed a danger to the community nor was a flight risk.

For Justice Samuel Alito, author of the majority opinion, that reading is “hard to swallow”. Requiring that the “alien must be arrested on the day he walks out of jail”—whether at the prison door or in the parking lot—unreasonably constrains ICE authority. With a granular analysis of the law's disputed adverbial clause (“when the alien is released”) and its relationship to “a series of adjectival clauses”, Justice Alito reversed the Ninth Circuit on grammatical grounds, throwing in a number of rhetorical digs. The law would amount to “nonsense” if it were understood to favour Mr Padilla and his fellow plaintiffs. It would be “ridiculous” to see the law as distinguishing between different classes of criminal aliens. Mandatory detention would be “downright incoherent” if it did not require the detention of every alien who has committed an offence listed in the law, at any time. In sum, the Secretary of Homeland Security “must arrest those aliens guilty of a predicate offence”. What of the immigrants’ claims that their “strong ties to the country” make a difference and raise “constitutional doubts” about being rounded up years after release from custody? That’s all quite irrelevant, Justice Alito responded. The law, as written, is clear.

If the majority opinion was penned with a schoolmarm’s icy attention to adverbial phrases, the dissent was crafted with a professor’s horizon-scanning view of the immigrant experience and the limits of government power. Justice Stephen Breyer wrote that Preap concerns “basic American legal values”. It has “consequences” for green-card holders who have “established families and put down roots in a community”. The ruling threatens to deprive people of their liberty without “due process of law”—in violation of the Fifth Amendment—and to strip them of “the longstanding right of virtually all persons to receive a bail hearing” when held in custody. Yet Justice Breyer’s dissent does not cede exegesis to the majority. “The language of the statute”, he wrote, “will not bear the broad interpretation the majority now adopts.” Instead, the law’s “ordinary meaning” and its “structure”, together with traditional interpretive tools, “all argue convincingly to the contrary”.

Capping his 14-page interpretive foray into the 1996 law, Justice Breyer addressed how the phrase “when the alien is released” should be read. The majority’s inclination to permit immigrants to be grabbed at any time in the future is wrong, he wrote, but the Ninth Circuit’s immediacy standard errs, too: when a parent asks a child to “mow the lawn, please, when you get home from school”, that doesn’t necessarily mean at the precise moment the child walks in the door. (“She can do a few other things first.”) A six-month limit, Justice Breyer wrote, is reasonable and squares with other detention timeframes.

A long-running disagreement over how to read statutes fuels the split between the court’s liberals and conservatives. Whereas the Alito majority in Preap takes a magnifying glass to the words on the page and strives to understand them without reference to anything outside the four corners of the document—an approach known as “textualism”—the Breyer dissent takes a broader view. As he wrote in his 2010 book “Making Our Democracy Work”, Justice Breyer “looks for the problem that Congress enacted the statute to resolve” and considers how the law was intended to resolve it. He also “examines the likely consequences of a proposed interpretation” to ask whether it serves the law’s purposes within America's constitutional design.

“I would have thought that Congress meant to adhere to [America's] values and did not intend to allow the government to apprehend persons years after their release from prison”, Justice Breyer wrote. To interpret the 1996 law otherwise is to do “serious harm to the principles for which American law has long stood”. In an era when immigrants—both legal and undocumented—face mounting pressure, Nielsen v Preap will do little to reassure them. Green-card holders with criminal records—no matter how distant—now have fresh reason to keep looking over their shoulders.