Travellers entering the United States, be aware: American border agents can still easily search your cellphone.

That's despite a much-publicized U.S. court ruling against border guards searching electronic devices without declaring prior grounds for suspicion.

Two Canadian immigration lawyers warn that last month's ruling from the U.S. Federal Court in Massachusetts is extremely limited in its effect — at least for now.

"My usual advice to my clients would not change," said Andrea Vaitzner, a Montreal-based immigration lawyer at Norton Rose Fulbright.

"I would still advise them not to save anything on their devices they would not want a [U.S. Customs and Border Protection] officer to read. I would suggest that they clean their phones and laptops and to save documents remotely in cloud storage."

She said U.S. border agents are not allowed to check documents that are stored remotely.

Limited ruling

On Nov. 12, a Federal Court in Boston ruled that searching a phone or laptop without reasonable grounds for suspicion is a violation of the U.S. Constitution's Fourth Amendment. The decision sided with a group of plaintiffs that included 10 U.S. citizens and a Haitian-born U.S. resident, the American Civil Liberties Union and the pro-privacy Electronic Frontier Foundation.

Plaintiffs alleged that border agents arbitrarily demanded access to their devices at U.S. airports and Canada-U.S. border checkpoints, including the U.S. customs preclearance zone at Toronto's Pearson Airport, the Ontario-New York checkpoint, and Quebec checkpoints with Vermont and New York.

One of the plaintiffs was a lawyer, whose device contained confidential exchanges with clients. Another plaintiff was a journalist, who was concerned agents would read his confidential discussions with sources.

Their suit came following evidence of a spike in U.S. border searches of travellers' personal devices.

Cars line up to cross into the U.S. at the border in Saint-Bernard-de-Lacolle, Que., in 2017. The number of electronic device searches at U.S. ports of entry has increased significantly, the ACLU says. (Don Emmert/AFP/Getty Images)

The Electronic Frontier Foundation celebrated the ruling, saying travellers could now cross the border without fear of being searched without grounds, because the court had put an end to the practice.

Not so fast, say two Canadian lawyers. Vaitzner and Toronto lawyer Henry Chang warn that the scope of the ruling remains limited.

They say its findings don't apply outside Massachusetts.

Chang, a lawyer with the Dentons firm and an expert on Canada-U.S. immigration issues, called the case a positive step in the protection of privacy rights.

But, he said, "Decisions of a federal district court are not binding in any other district."

In practical terms, Chang said, that means the verdict wouldn't carry immediate weight far beyond Boston's Logan Airport.

"So a U.S. [Customs and Border Protection] officer at Toronto International Airport is not bound by this decision. Neither is a USCBP officer at the Detroit-Windsor land border, or even Los Angeles Airport," he said. "None of these locations are within the [Federal Court] District of Massachusetts."

A passenger gets a laptop at a security checkpoint at LaGuardia Airport in New York City. (Carlo Allegri/Reuters)

He said he foresees only two ways this decision ends up becoming binding on all U.S. customs officers everywhere.

One is if the decision is appealed to the U.S. Supreme Court and gets affirmed by the high court.

The second is if U.S. Customs and Border Protection acknowledges the validity of the Nov. 12 decision and decides to incorporate it into its own guidance to staff.

"If this occurs, the guidance will apply at all ports of entry and preclearance offices," Chang said.

"Clearly, we are not at that point yet."

From the U.S. government's perspective, searches of electronic devices are essential to enforcing the law and protecting Americans, and affect less than .01 per cent of travellers who enter the country.

What is 'reasonable suspicion'?

The suit originally asked the court to require that border agents obtain a warrant to search an electronic device. But the court rejected that request.

Instead, the plaintiffs won on a narrower question: the court said border officers must articulate grounds for "reasonable suspicion" of illicit activity, if they want to perform a warrantless search.

As Vaitzner points out, the definition of that term is sufficiently vague to easily justify searches.

"If a traveller appears nervous, is that reasonable suspicion?" she said. "I do not think it will take much for a USCBP officer to form a reasonable suspicion and search a traveller's phone or laptop."