Europe has made its name as the top cop of tech regulation.

The European Commission, the executive arm of the European Union, has imposed a combined $9.5 billion in antitrust fines against Google since 2017, and its boss hints Amazon and Apple might be next in line.

Facebook, meanwhile, has been subject to probes from competition and data protection authorities across the EU since the region’s strict new set of privacy rules called the General Data Protection Regulation (GDPR) went into effect last year.

As U.S. regulators and lawmakers step up their efforts to reign in big tech companies, Europe offers some valuable lessons.