The Supreme Court has never heard a case challenging the government’s authority to search a computer. It is time, after a panel of the United States Court of Appeals for the Ninth Circuit opened the way last month to vast government intrusion. It ruled that, without good reason to suspect evidence of a crime, border agents could seize a laptop and open a dragnet search of files, e-mails and Web sites visited.

The majority pats itself on the back for stopping “far short of ‘anything goes’ at the border,” since any intrusion must not violate the Fourth Amendment’s ban on “unreasonable searches and seizures.” But by not requiring the government to have a reason for seizing a computer or to say what it is searching for, a dissent notes, the majority “allows the government to set its own limits.” In other words, pretty much anything goes.

The government asked the court to create this precedent, though in this case it had genuine grounds for suspicion. When the defendant crossed from Mexico into Arizona, his criminal record as a child molester came up in a database. When the government looked for child pornography, it found plenty on his laptop. The government has a duty to secure the borders against this and other kinds of illegal material, including drugs and weapons.

Fourth Amendment law already gives border agents huge leeway, allowing them to search travelers and their belongings, without a warrant, proof of probable cause or suspicion of illegal activity. The Ninth Circuit decided that computers could be searched on site as part of those belongings. But this ruling allows the government to hold a laptop for weeks or even months, transport it away from the border and subject it to an intensive search.