"Black Lives Matter" was a phrase used on Facebook after the killing of Trayvon Martin in 2012. Then it became a hashtag that's become a nationwide network using social media, making race an unavoidable topic of conversation in the last days of the Obama Administration. Protesters show up on TV news: denouncing police shootings, interrupting speakers, and blocking streets and highways. There's still no particular leader, but now the network is one of 60 black-led organizations formally demanding specific changes in public policy. Some claim it's indirectly responsible for the killings of police. Others call it the latest phase in the civil rights movement.