In this episode of Talk Nerdy, Cara is joined by the chair of Columbia University's psychology department, Dr. Carl L. Hart. They talk about his newest book, "Drug Use for Grown-Ups: Chasing Liberty in the Land of Fear." Discussed topics include: public misunderstanding about responsible drug use versus addiction, the racist underpinnings of the war on drugs, and how evidence-based policy could improve countless lives. Follow Carl: @DrCarlHart.