cameras
san francisco installed a bunch of big brother style cameras all over the city. they figured they'd catch criminals. and crime rates have gone down. would be criminals think twice before becoming actual criminals. it's kinda hard to assert innocence when there's video of you doing what you said you didn't do. but that's only part of the story. the other side of the coin is these cameras are protecting the non-criminals. it's really hard to convict someone of doing something witnesses said he did when video shows he didn't. and yeah, it's a pretty serious reduction in privacy. but it's a good trade. for cops too. confrontations are much less likely to become violent when cameras are involved. bystanders filming police actions are much more likely to save a cop's life than to take it.