There is a recurring idea in some science-fiction stories; A technology that comes along that lets you see an occurrence in the past. You punch in the time and place and you see what was happening at that spacetime. Theoretically it would be used for historical events in the distant past. How involved was Brutus in the Ides of March. Was Cleopatra a looker? Did Judas invest his thirty pieces of silver wisely, or did he blow it on beer and whores? The distant past doesn’t break privacy legislation.
If we had such a device, it would certainly change the world. If you wanted to try and find a famous terrorist, you could just plug in a time and place that you knew he was at, and then keep following him around until you find out where he was at the present. Nasty political issue solved.
But let’s wonder about more local problems. Solving crimes would be a snap, when anyone can become a witness to any event. Unabomber style antics would be a lot more popular because its would still be nearly impossible to trace the origin of a package.
But let’s say there was a cost involved in using this technology. It obviously can’t be free. Nothing is.
If it was $100, could you offer it as a service to citizens. If a crime has been committed against you, could you pay $50 to get definite proof of who did it, and then have the perpetrator pay the balance as part of the judgment against them.
And most importantly, could you use it to find the malicious idiot who decided it would be a good idea to leave his chewed gum in a place where someone could walk in it.