New York City's hijacked hashtag launches a global conversation on police brutality

When the New York Police Department encouraged its followers on Twitter to share photos of themselves with NYPD officers, the result was not what they expected. Two days later, the hashtag has been mimicked in a half dozen cities around the world to showcase police brutality. But the social media effort has had another consequence: it has started a global dialogue about the perception of police and policing in different cities.