How effective is a cigarette ban in curbing smoking among youth?

Some countries are moving towards stopping the next generation from ever legally being sold cigarettes. The British government recently proposed a ban on selling cigarettes to anyone currently 14 or younger, in hopes of creating the first "smoke free generation." New Zealand has passed a similar law. Michael Chaiton, senior scientist at the Centre for Addiction and Mental Health in Toronto, weighs in on these bans and speaks to the Canadian context.