A court opinion written in 2004 and released for the first time last week rubber-stamped the NSA's mass collection of online "metadata" that is, information on the senders, recipients and timing of e-mails and other communications, though not their content.
The Bush administration had begun the wholesale collection of such information unilaterally, but it was forced to present the program to the court for ex post facto review after top Justice Department lawyers threatened to resign.
Under a Supreme Court ruling in 1979, well before most people had imagined such a thing as an e-mail, metadata is not subject to constitutional protections against unreasonable search and seizure. Federal law sets a very low bar for authorities to access such data: They have only to certify that it's likely to yield information that is "relevant" to an investigation.
However, as George Washington University law professor Orin Kerr recently noted on the blog Lawfare, the statute was obviously written to apply to specific investigations and targets. The FISA court nevertheless relied on it to approve the continued collection of an "enormous volume" of Americans' online data.
While the court did attempt to impose rules and restrictions on the data dragnet, the documents show that the NSA repeatedly failed to comply with them. And yet online metadata collection continued until 2011, when the Obama administration discontinued it for what it called "operational and resource" reasons.
Meanwhile, a similar program collecting Americans' telephone metadata en masse, under a similarly dubious legal rationale, apparently continues to this day.
The ACLU is now suing to stop the NSA's mass collection of phone records. Arguments in that case were heard in U.S. District Court in New York and it passes for progress that we know that much.