US border officials have gone too far in conducting unauthorised searches for illicit digital content on mobile phones and other electronic devices, a court ruled, potentially dealing a blow to broader government efforts to police the online world.

The number of probes into electronic devices soared from 8,503 in the 12 months to end-September 2015 to 30,200 in the year to 30 September 2017, US Customs and Border Patrol figures showed, prompting a backlash from privacy groups the American Civil Liberties Union (ACLU) and Electronic Frontier Foundation (EFF).

While officials claimed such searches are necessary to combat a range of crimes including terrorism and child pornography, the court ruling means border guards must now demonstrate reasonable suspicion before asking for access to devices.

The ruling came following a lawsuit filed by ACLU and EFF in 2017 on behalf of 11 individuals who claimed to have been subjected to unwarranted investigations. The court stopped short of requiring officials to obtain clearance to conduct such probes, but ruled they must back up requests to search devices with “specific and articulable facts”.

Growing conflict
The decision comes as global governments become increasingly concerned about the potential security risks posed by digital content, with specific worries involving encrypted data and communications.

Emerging technologies are posing tough questions for established privacy and security laws regarding the level of access authorities can, or should, have.

Perhaps the highest-profile example of this to-date was a case in 2016 involving the FBI and Apple, in which investigators reportedly resorted to hacking the iPhone of a suspected shooter.

There are also broader privacy concerns around the information stored by big tech and social media companies.