What Conceivable Statement of Facts Could Have Produced this Order?

[See below for an important correction to this post] I confess myself at a bit of a loss to understand the FISA Court order that Steve discussed earlier and that Glenn Greenwald disclosed at the Guardian. As Steve noted, the order required Verizon Business Network Services, under Section 215 of the Patriot Act,

to produce to the National Security Agency (NSA) upon service of this Order, and continue production on an ongoing daily basis thereafter for the duration of this Order, unless otherwise ordered by the Court, an electronic copy of the following tangible things: all call detail records or "telephony metadata" created by Verizon for communications (i) between the United States and abroad; or (ii) wholly within the United States, including local telephone calls.

The order---assuming it hasn't been since modified or contravened---lasts for three months, beginning the day of the Boston Marathon bombings and ending in mid-July. We have only the order itself, not the application that underlies it, but I have a hard time imagining the application that could have produced it. Section 215, codified in law as 50 U.S.C. § 1861, allows the government to apply to the FISA court for an order for production "of any tangible things . . . for an investigation to obtain foreign intelligence information not concerning a United States person or to protect against international terrorism or clandestine intelligence activities. . . ." To acquire such an order, the government does not have to do much---just as it doesn't have to do much in a criminal investigation: It merely has to offer, in pertinent part, "a statement of facts showing that there are reasonable grounds to believe that the tangible things sought are relevant to an authorized investigation . . . to obtain foreign intelligence information not concerning a United States person or to protect against international terrorism or clandestine intelligence activities." So I'm trying to imagine what conceivable of facts would render all telephony metadata generated in the United States "relevant" to an investigation, presumably of the bombing. This would include, of course, all telephony metadata that, as matters turned out, postdates the killing of one bomber and the capture of the other---though there's no way the government could have known that when the application was submitted. And it would also include all telephony metadata that postdates the government's conclusion that the Tsarnaev brothers were apparently not agents of any foreign terrorist group. But even if this were not the case, how is it possible that all calls to, say, Dominos Pizza in Peoria, Illinois or all calls over a three month period between two small businesses in Juneau, Alaska would be "relevant" to an investigation of events in Boston---even if we assume that the FBI did not know whom it was investigating in the Boston area and did not know whom that unknown person was communicating with? I think the only possible answer to this question is that a dataset of this size could be "relevant" because there are ways of analyzing big datasets algorithmically to yield all kinds of interesting things---but only if the dataset is known to include all of the possibly-relevant material. The data may not be relevant, but the dataset is relevant because it is complete---and therefore is sure to include any communications by whomever the bombers turn out to be. The trouble is that if that constitutes relevance for purposes of Section 215---or for purposes of grand jury subpoena, for that matter---then isn't all data relevant to all investigations? CORRECTION: this post incorrectly identified the start date of the FISC order as the date of the Boston bombings, i.e., April 15.  That was incorrect: the order was in fact signed on April 25.  As written this morning, the post had assumed---based upon the order's timing---that the collection activity had to do with the Boston investigation.  But, as Wells later noted, Senate Intelligence Committee members now claim that the collection is longstanding and regularly re-authorized---and thus not necessarily directed at issues arising from the Boston case.