In the current discussions of NSA surveillance, we often talk as though metadata and cell phone tracking are simple creatures of government power. It is government, after all, that collects bulk metadata. And it is government that runs the surveillance programs that scare us most. But it is worth remembering that actual use of this sort of data---and the winners and losers associated with its collection, retention, and use---is far more complicated than that. Yesterday, I got such a reminder.

I received a call from an old friend, Steve Benjamin. Benjamin is a Richmond defense lawyer, with whom---a number of years ago---I worked on the grotesque case of a man with no prior criminal record who was serving a lifetime in prison for a crime he pretty clearly did not commit. Because of the Byzantine rules of post-conviction review in Virginia at the time, there was no obvious way to get Jeff Cox's innocence claims before a court---even though, by that point, the FBI doubted the integrity of the conviction and was investigating other people for the crime for which Cox was serving time. I wrote a string of editorials about the case, and over the succeeding few years, I also wrote a long series of editorials about the procedural rules in Virginia that made it so hard to free Cox (which did, by the way, eventually happen). Some of those rules have since been relaxed. It was a case that arouses intense feelings in everyone who played a role in setting it right---including, by the way, a then-federal prosecutor in Virginia named James Comey. So it was with some emotion that I heard Steve say, "we have another Jeff Cox situation."

The situation Steve described is not normal Lawfare fare: his client, one Mark Weiner, was prosecuted and convicted in Albemarle County for abducting a woman and is now awaiting imposition of what will be a lengthy prison sentence. For a variety of reasons, Steve and his redoubtable partner, Betty Layne DesPortes, believe that the victim fabricated the crime, and they have filed a motion to set aside the verdict in the trial court. What may catch the eye of Lawfare readers is that much of the evidence they cite that Weiner could not have committed the crime in question involves telephony metadata and cell phone location data of precisely the type whose use and collection is so controversial when NSA handles it.

The victim had testified that her cell phone was dead, so she could not call 911 or respond to calls from the police during the episode. The records, according to the motion, show that she used the phone while it was supposedly dead to call her boyfriend, to take a call from him, and to retrieve a voicemail message from the 911 dispatcher. What's more, her phone was accessing cell towers near her mother's apartment, the motion alleges, but never accessed the cell towers near the abandoned house where she claims to have been held. The phone of the alleged perpetrator also generated data that Benjamin and DesPortes claim is inconsistent with the prosecution's theory of the case: GPS data from his phone shows it would have been at least 17 miles from the abandoned house. The motion is a compelling read, and the reason it's compelling is precisely because the cell site data and call records data are powerful stuff.

My point here is not that Mark Weiner is innocent, as Benjamin claims. I have not studied the case with the intensity it would require for me to have an opinion about that---other than the strong feeling that Benjamin and DesPortes have raised serious questions that I would hope any good trial judge would take very seriously.

My point, rather, is simply to illustrate both that this sort of data can be enormously probative and that it can work to rebut government theories, as well as to bolster them. That's not a controversial point. And it's not necessarily an argument for broad collection authorities either. It is a reminder, however, that data, even Big Data, is not the enemy. Big Data is a tool that cannot be evaluated until someone picks it up to use it. Sometimes, that tool will represent a boon to government surveillance practices and a threat to individual liberties, but sometimes it will be a scrappy pair of defense lawyers who wield it on behalf of a client they want to convince a court was convicted of a fictitious crime. When AT&T purges metadata and cell-site data, it isn't just NSA and the FBI whose interests suffer. Mark Weiner's do too. If you doubt that, read this motion and imagine trying to write it without recourse to any of the telephony data Weiner's lawyers cite.