The European Court of Justice (ECJ) ruled in favour of Germany’s anti-cartel watchdog, which had argued that it could take data privacy issues into account when considering antitrust cases.

One of the key issues in the case was Meta’s ability to link data across platforms, which allows it to closely target adverts at users, the principal way it makes money.

The German watchdog barred Meta from mixing personal data gathered on Facebook with details harvested from Instagram or WhatsApp, arguing that it amounted to an abuse of its dominant market position in Germany.

The European court said cartel offices were within their rights to carry out investigations under the EU’s huge data protection regulation (GDPR).

“The judgment will have far-reaching effects on the business models used in the data economy,” tweeted Andreas Mundt, head of the anti-cartel watchdog.