US border control officials have asserted nearly unlimited authority to search the laptops, cell phones and other electronic devices belonging to travellers arriving in the United States. A federal judge last week ruled that such warrentless searches are unconstitutional.

The ruling was a victory for the American Civil Liberties Union (ACLU) and the Electronic Frontier Foundation, which filed a lawsuit on behalf of 11 travellers whose devices were searched without probable cause at US border entry points.

“The court said today that suspicionless searches at the border of cell phones and laptops violate the Fourth Amendment,” said Jessie Rossman, a staff attorney at ACLU’s Massachusetts chapter.

The civil-rights groups said the ruling means that border agents must now demonstrate individualised suspicion of contraband before conducting such searches.

In 2018 alone, US Customs and Border Security agents conducted about 33,000 searches of electronics devices being carried into the country. The number of such searches has been steadily rising in recent years.

The US government has defended the searches as necessary to protect the public. Information gleaned from such searches has been used in a variety of investigations, including enforcement of tax, bankruptcy, environmental and consumer protection laws, gathering intelligence, and criminal investigations, according to federal documents submitted in the court case.