The streets in many U.S. cities have erupted with protests recently and police and federal officers have fired rubber bullets and other projectiles into crowds, injuring or even blinding some of the participants. This has been going on for decades, yet efforts to crack down on less-lethal ammo have failed locally and nationally. KHN senior correspondent Jay Hancock spoke with NPR’s Ailsa Chang on “All Things Considered” about why efforts to curb their use have failed.