France’s highest appeals court, the Cour de Cassation, ruled on Monday that a passcode could be regarded as a “decryption key” and refusing to hand it over was punishable by up to three years in jail and a massive fine.

Campaign group Fair Trials said in a statement that everyone had the right not to incriminate themselves, describing it as “an essential guarantee of a fair trial”.

“Forcing people to open their mobile phones threatens this right,” said the group’s Ilze Tralmaka.

“People should not be forced to actively cooperate with an investigation against them under the threat of criminal conviction.”

The court was considering the decisions of several lower courts stretching back to 2019 when a man was convicted of cannabis possession but acquitted of refusing to hand over his passcode.

The decision was upheld on appeal, rejected on higher appeal but reaffirmed by the lower court, which refused to change the decision.

Prosecutors eventually took the case to the country’s highest appeal court arguing that the initial trial judge had wrongly excluded phone passcodes from the legal definition of “decryption key”.

The Cour de Cassation agreed and ordered the case to be retried.