California's Dianne Feinstein, the ranking Democrat on the Senate Intelligence Committee, is planning to re-introduce legislation requiring Facebook Twitter, YouTube and other social media to alert federal officials about terrorist activity online. They've beaten back such proposals before. But the tech firms, the FBI and the NSA aren't the only agencies monitoring social media. The LAPD and local sheriffs are also in on the act. And electronic monitoring isn't the only tool being used by local police.