This isn't a new idea - it's been around for a number of years already, with many state prison systems getting in on it. If I'm not mistaken, it's the only deck available in the commissary for most the prisons that sell them, thus forcing them into distribution and getting them in front of the maximum number of prisoners. I don't know of any statistics as to their efficacy, but I'd imagine there were a few cases where someone snitched and solved a murder or two.