There are some 680,000 sworn police officers in the United States. Thanks to a year of cellphone videos spread on social media, "every one of them has had to answer, in one way or another, for the actions of colleagues they will never meet." Such videos of shootings, beatings and apparent racial profiling have reduced public confidence in police all over the country. When every local encounter has the potential for national news coverage, street cops say, "Everything is just harder." Many departments are engaging in damage control by re-training officers to think of themselves as guardians, rather than warriors. But critics say that's not enough -- that the justice system is rigged in the cops' favor, and the only true reform is to hold them accountable.