Why Are We Expanding Background Checks?

CNN's John Sutter asks David Frum what he thinks would have prevented the mass shooting in Las Vegas. Frum says we don't train police officers to be warriors, but they are trained for valor and protecting their own lives. He argues that background checks wouldn't have stopped this or other shootings; there is a cultural rot issue as well.Frum: I'm trying to give us the best odds within our legal framework for preventing future death.