The term used to explain why 12 sensible people would acquit, despite witnesses and physical evidence, is the “CSI Effect.” That’s where juries expect conclusive scientific evidence like they see on TV. If they don’t get it, they assume the case is weak or the accused is innocent. It seems ridiculous, but we tend not to select the bets people for juries, as smart people duck their duties.

This story is another example of how television is warping the public’s ability to understand the world.

We’ve frequently talked about law enforcement and the intelligence community accessing and making use of cell site location data, which looks to figure out where people are based on what cell towers they’re connected to. Law enforcement likes to claim that it doesn’t need a warrant for such data, while the NSA has tested a pilot program recording all such data, and says it has the legal authority to collect it, even if it’s not currently doing so.

However, as anyone with even a basic geometry education recognizes, which cell tower you’re connected to does not give you a particularly exact location. It can be useful in putting someone in a specific (wide) area — or, much more useful in detailing where someone is traveling over long distances as they repeatedly switch towers in a particular direction. But a single reading does not give you particularly exact location details. I had naturally assumed that most people understood this — including law enforcement, lawyers, prosecutors and judges — but it turns out they do not. A rather depressing story in The Economist notes that, thanks to this kind of ignorance (combined with bogus cop shows on TV that pretend cell site data is good for pinpointing locations), cell site location data is frequently used to convict innocent people.

We should not expect the average person to understand how their gadgets work. Probably 90% of people have no understanding of their car’s engine and that technology has been with us for a long time. It is also much easier than cell phone technology or network technology. Cops are no brighter than the general public so they can’t be expected to know this stuff either. Prosecutors and judges have the power to take a man’s freedom away so that’s a problem.

SOMEONE strangled a prostitute in Portland, Oregon in 2002. The police arrested Lisa Roberts, the victim’s ex-lover, who spent more than two years in custody awaiting trial. Shortly before the trial the prosecutor told Ms Roberts, via her lawyer, that tower data collected by Verizon, her mobile-telephone network, showed precisely where she was at the time of the murder. As her lawyer recalled, the prosecutor said Ms Roberts could be “pinpointed” in a park shortly before the victim’s naked and sexually assaulted corpse was found there. She was told she faced 25 years to life in prison. She accepted a deal to plead guilty and serve 15 years.

But the high-tech evidence against her was bunk. Routinely collected tower data can place a mobile phone in a broad area, but it cannot “pinpoint” it. That would require a special three-tower “triangulation”, which cannot reveal past locations. It took a decade for Ms Roberts’s guilty plea to be thrown out. On May 28th she left prison, her criminal record clean, after nearly 12 years in custody.

The problem here is that even if the accused knew the DA was lying, she could not be sure the jury would understand that the DA was lying. The defense attorney probably lacked the knowledge and resources to fight it. That opens the door for the many crooked prosecutors to make claims about technology, like in this case, that are batshit crazy, but may fly with a jury or a gullible defendant.

This really points to a larger issue: people have this tendency to believe that technology can answer all questions. The NSA’s fetishism of surveillance via technology is an example of this. There’s data there, so it becomes all too tempting to assume that the data must answer any possible question (thus, the desire to collect so much of it). But the data and the interpretations it can lead to are often misleading or simply wrong. And that’s especially true when dealing with newer technologies or forms of data collection. That the criminal justice system could go decades without everyone recognizing the basic geometric limits of cell site location data based on a single cell is… both astounding and depressing. But it’s also a reminder that we shouldn’t assume that just because some evidence comes from some new-fangled data source it’s automatically legitimate and accurate.

This is why the NSA spying stuff is mostly bullshit. The government buys all of its technology from the private sector. There are things done for the government by private contractors that are not for anyone else, but the government does not have special magic. Further, the government is not getting the best and brightest. There’s way too much money to be made in the private sector for the government to get the best and brightest.

More important, the volume of data involved is so large there’s simply no way to sort through it in a meaningful way. There are 150 billion e-mails sent every day. That’s 55 trillion e-mails a year. Searching that volume of records for useful data is simply impractical. Throw in the 100 trillion or so phone calls and probably the same number of texts and the volume of data is well beyond what could be useful. That’s why they don’t try, but they’re fine letting people think it. The Feds are relying on the CSI effect to convince the world they can read your mind.