Europe’s GDPR has just dealt its biggest hammer blow yet. Almost exactly five years since the continent’s strict data rules came into force, Meta has been hit with a colossal €1.2 billion fine ($1.3 billion) for sending data about hundreds of millions of Europeans to the United States, where weaker privacy rules open it up to US snooping.

Ireland’s Data Protection Commission (DPC), the lead regulator for Meta in Europe, issued the fine after years of dispute about how data is transferred across the Atlantic. The decision says a complex…