Government attorneys had argued that the Constitution didn't address the use of private email and phone call data.

The US had charged Hasbajrami in 2011 with providing material support to a terrorist group in Pakistan, and the suspect initially pleaded guilty to one of the charges after his counsel told him that there were no warrantless wiretaps involved. However, the US later admitted that it had studied Hasbajrami's email without a warrant, leading him to withdraw his plea and ask the appeals court to toss out evidence gathered through FISA Section 702.

The decision kicks the case back to its original district court with the constitutional considerations in mind. This won't necessarily help Hasbajrami avoid prison, and it effectively defends a key part of the NSA's mass surveillance. If the ruling holds, though, officials might have to think carefully about searching NSA data and putting it to use.