MELISSA BLOCK, HOST:
And now to that other story I mentioned. It's no secret that police search social media. It's useful for investigations and if a posting is public, there's no need for a court order. But now, some police are using powerful social media monitoring tools for their searches. As NPR's Martin Kaste reports, the software is making even some cops nervous.
MARTIN KASTE, BYLINE: When you search Twitter, you're not actually searching the whole thing. There are millions of tweets a day, and it's technically impossible to search all that from the Twitter page. But you can if you have something called Bluejay.
(SOUNDBITE OF NOTIFICATION TONE)
TYSON JOHNSON: Let's see what pops up.
KASTE: Tyson Johnson is vice president at the company that makes this product, which is meant for security operations and police departments. It lets them search the entire Twitter firehose, as Johnson calls it.
JOHNSON: You can imagine - if you had 1,500 gang members, like we do in Detroit, we have their handles so we're able to identify what the gang members are doing.
KASTE: And where they're doing it, at least the ones who leave their location settings on. He plugs in the search term "weed" and the pertinent tweets pop up on a map.
JOHNSON: You see how somebody has their GPS on here. So if we have a history of that person tweeting over, say, a month or two-month period, you can run it through another technology called Geotime; and it'll actually plot for you by time, date, location, where that individual goes.
KASTE: Now, keep in mind, this is not a case of the police asking the phone company for data. The information is already public. People are voluntarily tweeting what they think, where they are, and what they photographed. Social media monitoring actually comes out of the world of marketing. Companies use similar tools to track what people are saying about their brands. It's just that now, the police have discovered it.
Vernon Keenan is director of the Georgia Bureau of Investigation.
VERNON KEENAN: It's like a stakeout, you know. If persons are talking about - you know, about criminal activity, it alerts us to it.
KASTE: But here's the thing. While the companies selling these services say the police should feel free to scan social media, some police are hesitant. Keenan is one of them.
KEENAN: What public can do, law enforcement cannot do.
KASTE: Yes, he says, tweets are public. But there are plenty of public things that the police are not supposed to monitor - say, political rallies.
KEENAN: For law enforcement to be there and to take photographs of all the participants, monitoring is not against the law. But it's not acceptable.
KASTE: So Keenan requires his agents to get a supervisor's permission before they monitor social media. They have to lay out what they're searching for, and why. It seems like overkill, forcing cops to ask permission just to search the public Internet. But cops are different. Ryan Calo is a professor at the University of Washington Law School. He says there are certain kinds of searches that a police officer should be careful of.
RYAN CALO: If officers were looking on the basis of gender and then making decisions on that basis, you could run into constitutional scrutiny. And you would be almost sure to, if your keyword involved the word Muslim.
KASTE: But beyond protected classes like race and religion, Calo says the law on this is pretty unclear. Police departments don't like to talk about their monitoring, and no one is eager to become a test case. Calo says there may be no legal barrier to the police scanning Twitter for political keywords - say, #occupy - but he says that doesn't mean they should.
CALO: Any police officer, you know, ought to sort of think through a kind of publicity principle; which is, if it were to get out that we did this exact search, what would the public reaction be, and what would the constitutional import be?
KASTE: Which brings us back to Vernon Keenan, at the Georgia Bureau of Investigation. He's been campaigning to get more police departments to set up rules for social media monitoring. He wants to avoid a backlash that might deprive cops of a useful tool. Last fall, he gave a speech to the International Association of Chiefs of Police, warning them that social media scanning was a kind of hot stove.
(SOUNDBITE OF RECORDING)
KEENAN: And know what happens when you touch a hot stove - you get burned.
KASTE: As you might guess from that audio quality, the speech was recorded by someone in the audience, and uploaded to the Internet. The funny thing is even before Keenan sat down, he knew he'd been recorded because one of his colleagues up on the dais had been monitoring Twitter.
Martin Kaste, NPR News.
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