The move is a problem for Facebook which has disputed the Belgian regulator's power.

The EU Court of Justice (CJEU) said that a national supervisory authority may exercise its power to bring any alleged infringement of the GDPR before a court of a member state, even though that authority is not the lead supervisory authority about that processing.

The CJEU got involved after a Belgian court sought guidance on Facebook's challenge against the regional competence of the Belgian data watchdog's bid to stop the company from tracking users in Belgium through cookies stored in the company's social plug-ins, regardless of whether they have an account or not.

The move could see US Big Tech facing privacy challenges in different jurisdictions creating an endless legal mess.