Well, I love the idea of giving law enforcement personnel tools that will help them catch criminals and enforce the law... At the same time, you don't want to start down a road that has a CCP-style surveillance state at the other end... Governments (especially leftist ones) are terrible at putting the breaks on this sort of thing to stop it going too far!

Maybe there needs to be legal safeguards in place to make sure this technology is not abused. Maybe there are - I'm not very familiar with this sort of thing.