Editorial: Border agents shouldn’t be allowed to trawl through the contents of your phone

International travelers grudgingly accept that their cellphones or laptops might be handled and given a cursory inspection at an airport or border crossing. But some travelers, including U.S. citizens, have had the contents of their electronic devices — including family photographs and personal information — scrutinized by border agents.

A federal judge in Boston rightly held this week that such searches may be carried out only if the authorities have a reasonable suspicion that the devices contain contraband such as classified national security information or child pornography.

U.S. District Judge Denise J. Casper ruled in a case brought by 11 plaintiffs — 10 U.S. citizens and one lawful permanent resident — whose devices had been searched when they entered the country. Among them was a Muslim woman who twice had her iPhones searched despite her objection to having Customs and Border Protection officers view photographs of her and her daughters without their headscarves.

Traditionally the courts have treated searches at the border as an exception to the 4^th Amendment’s ban on “unreasonable searches and seizures” because of the nation’s interest in intercepting contraband. But Casper noted that the exception was meant to cover “routine” searches, not the intrusive inspection of electronic devices that are notable for the vast quantity of personal information they contain.

Casper isn’t the first judge to rule that border searches of electronic devices require reasonable suspicion. In 2013, the U.S. 9th Circuit Court of Appeals established that standard even as it upheld the forensic analysis of the laptop of a man returning from Mexico that turned up images of child pornography. (The court said that the fact that the man’s name was on a watch list of sex offenders had created reasonable suspicion.)

But it’s significant that this week’s ruling follows — and refers to — a 2014 Supreme Court decision that broke new ground in recognizing that searches of devices such as smartphones and laptops pose a special threat to privacy. As Chief Justice John G. Roberts Jr. wrote in that ruling: “Modern cellphones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse.”

The 2014 ruling involved the search of a cellphone belonging to a person under arrest, and the court held that before trawling through its contents police had to obtain a search warrant by showing they had probable cause to believe that a crime had been committed.

Because of the special circumstances of border searches, Casper’s ruling requires only reasonable suspicion, a lesser standard that CBP and Immigration and Customs Enforcement say they already employ in conducting so-called advanced searches of electronic devices, those that involve connecting external equipment to a device. Casper’s ruling rightly requires reasonable suspicion before a border agent can conduct even a “basic” search of a device’s contents.

This ruling recognizes that trawling through a traveler’s phone or laptop for no reason is a 21^st century violation of the 4^th Amendment. When a suitable case presents itself, the Supreme Court should make the same call.