There is a long-standing debate over the fact if the advertisements of de-merit goods be taxed more or they should entirely be banned. Perhaps, the reason why government has totally banned them is that it would seem very hypocrite on screen where there is one commercial selling cigarette while the next showcases government sponsored advertisement, advising people to stay away from it. The government, on the similar lines can practice negative advertisement, which will most likely persuade people to stay away from it and emphasize on the dangers of cigarettes, alcohol or addictive drugs. This is bound to negatively impact the demand curve and shift it left.
Also, economically, a contraction in demand can be achieved by contraction of demand curve subjected to imposition of tax, raising the prices and shifting the supply curve to the left. A tax equivalent of marginal external cost should be imposed so that an out, which is socially optimum, can be achieved. In practice, however, an accurate monetary value is difficult to arrive at, to curb the consumption of such goods. The impact of regulation is rarely complete to eliminate the demand since the product is then usually driven by the hidden or unofficial market in these cases. Spatial restrictions, which are less severe in nature, are also sometimes helpful in regulatory control.