Facebook and other big tech companies have just lost big time in Europe.
They might soon be forced to radically change the way they deal with user data after the European Union's top court ruled Tuesday that they can't simply hand it over to U.S. authorities.
The court declared invalid a 2000 "Safe Harbor" agreement that allowed Facebook and other tech firms to transfer users' data in huge quantities to their servers in the U.S. More than 4,000 companies, including giants like Google and Amazon, took advantage of the agreement.
The ruling could complicate life for the tech companies and U.S. intelligence services, and hurt Europe's economy.
The U.S. slammed the ruling. "We are deeply disappointed in today's decision from the European Court of Justice," said Penny Pritzker, U.S. Secretary of Commerce. "[It] creates significant uncertainty for both U.S. and EU companies and consumers, and puts at risk the thriving transatlantic digital economy," she added.