The verdict delivers the first significant US courtroom loss for big tech in the years-long campaign by rivals, regulators, and prosecutors to tame the power of internet gatekeepers.

The lawsuit next moves to a remedies phase, meaning a judge as soon as the coming weeks will hear arguments about and decide whether to order changes to Google's business practices. Users of devices powered by Google's Android operating system could find more app options at lower prices if Google is forced to allow downloads of rival app stores from Play or share a greater portion of sales with developers selling digital items inside their apps.

The ruling came in a case first filed in 2020 by Epic Games, which argued since early November. The jury of nine only took three hours before reaching its verdict. They faced 11 questions, such as defining product and geographic markets and whether Google engaged in anticompetitive conduct.

Epic had accused Google of restricting smartphone makers, wireless carriers, and app developers from providing any competition to the Play store, which accounts for over 95 per cent of all downloads onto Android phones in the US.

Google denied any wrongdoing, saying its sole aim was to provide users with a safe and attractive experience, especially as it faced competition from Apple, its iPhone, and its App Store.

It is unclear where this will leave Apple, which has had more success in its anti-trust cases so far and yet has considerably more power over its app store users.