The Electronic Frontier Foundation yesterday won permission to lawsuit against AT&T, which has been aiding the NSA by siphoning off information about communications passing through its networks for pattern analysis. You can read the full decision, listen to a conference call with EFF attorney Cindy Cohn, or check out Orin Kerr’s analysis of the ruling. The short version is that the government can’t just quash judicial scrutiny into its surveillance activities just by shouting “national security” unless it provides some reason to think that any investigation will actually tend to undermine security: If don’t want to disclose particular pieces of information, they can make the argument on a case-by-case basis to a judge. Kerr also notes the presiding judge’s surprisingly bold statement (which is dicta, but interesting nonetheless) that “AT&T cannot seriously contend that a reasonable entity in its position could have believed that the alleged domestic dragnet was legal.”