It can be enforced in multiple ways. For instance by going after the European ad business or just yesterday a ruling of the European Court of Justice was publis

It can be enforced in multiple ways. For instance by going after the European ad business or just yesterday a ruling of the European Court of Justice was published stating that Europeans who run a "Facebook Page" take some of the responsibility http://curia.europa.eu/juris/document/document.jsf?text=&docid=202543&pageIndex=0&doclang=EN&mode=req&dir=&occ=first&part=1&cid=298398 http://curia.europa.eu/juris/document/document.jsf?text=&doc... (this s not about GDPR, but older rights, but shows how European organizations can go after US corps)