A sign outside a medical marijuana dispensary in Manitou Springs, Colo. Voters amended the state's constitution to legalize marijuana for recreational use in November 2012. Eric Whitney hide caption

itoggle caption Eric Whitney

A package of K2, a concoction of dried herbs sprayed with chemicals sometimes called synthetic marijuana. New York moved to ban a wide range of products like these this week. Kelley McCall/AP hide caption

itoggle caption Kelley McCall/AP