There is a distinction here that needs to be emphasized. We should absolutely allow people to smoke: what we should limit is the amount of money that goes into marketing, promotion, the big Philip Morris, government lobbying, and a whole bunch of backend work that goes into getting people addicted to Tobacco.

Simply restricting people from smoking is a blanket encroachment of personal liberty and should not be IMO entertained. As far as it doesn't damage others (like Guns), we should allow it.

I think warning labels on Cigarette boxes is an excellent idea - it informs the consumer of facts of consuming the product, whether they choose to do it or not is up to them.