Court documents unsealed on Thursday revealed that in 2008, the U.S. government threatened to fine Yahoo $250,000 a day if the company did not give up user communications.
In a statement, Yahoo said it was "required to assist the U.S. government in acquiring foreign intelligence information through the surveillance of targets reasonably believed to be located outside the United States." The company refused, arguing it was unconstitutional and violated users' Fourth Amendment rights. The government took its case to the Foreign Intelligence Surveillance Court, which ruled that Yahoo needed to comply. The company was threatened with the $250,000 daily fine after it decided to file an appeal, but then began to cooperate while still fighting; Yahoo later lost the appeal.
This decision, The Washington Post reports, was a "key moment" in the development of PRISM, the program that gave the NSA broad authority to obtain data from tech giants like Facebook and Google through secret court orders. Through PRISM, the NSA was able to gather more than 250 million communications in 2011 alone.