It’s 100 years since drugs were first banned, and drug use and drug crime have continued to grow steadily across the world. What are people addicted to? Are any of the policies adopted around the world based on scientific data? Are any of them working? Hari is the author of Chasing The Scream: The First and Last Days of the War Against Drugs; Hitchens is the author of The War We Never Fought. Chaired by Hernando Alvarez, editor of BBC Mundo.