USA Today's David Heath tells us about the popular types of social media sites used to promote white supremacist ideologies, and details how attempts to curb these ideologies have only recently gained more attention--and with limited success.

Trying to limit domestic terror and mass shootings should be simple, but it's not. Byron Tau of the WSJ lays out why the US Constitution is restraining the FBI's ability to reduce mass violence, and possibilities for working around it.