said by ArrayList:it's impossible to prove a negative.
It is impossible to prove an untestable negative condition. But for any other type of negative condition, provided that the universe of testable conditions is a closed one, such conditions can and are proven. It happens in computer science every day.
But my proposal is certainly not untestable. Surely law enforcement can provide a list of cases in which a lack of text message logs resulted in an accused person being acquitted. I'd even apply the same test to these of unmanned aerial drones by state and local law enforcement.