This is no surprise; if phone metadata of US citizens is legal to harvest, then social network metadata collection, which is essentially the same, is also legal

This is no surprise; if phone metadata of US citizens is legal to harvest, then social network metadata collection, which is essentially the same, is also legal to harvest. It looks like this collection is limited only to metadata, if this can be believed: "The legal underpinning of the policy change, she said, was a 1979 Supreme Court ruling that Americans could have no expectation of privacy about what numbers they had called. Based on that ruling, the Justice Department and the Pentagon decided that it was permissible to create contact chains using Americans’ “metadata,” which includes the timing, location and other details of calls and e-mails, but not their content. The agency is not required to seek warrants for the analyses from the Foreign Intelligence Surveillance Court." So, as long as that 1979 Supreme Court ruling is not modified, this collection is legal. I'm a bit surprised it's the NSA and not the FBI, but if you're going to track the intersection of foreigners or U.S. citizens, one agency has to be picked over the other, and they picked the NSA.