- But since the Market Demand Schedule is nearly vertical, the total purchased quantity of the prohibited product is only minimally reduced in the short run by the increased prices of the black market. As illustrated by the demand schedule (violet) in the graph, Q (the quantity demanded) is affected only to a minor degree by changes in price. As we shall show in Section 5, long-run consumption of such products may even be encouraged by legal prohibition, since the latter presents legal obstacles both to medical researchers seeking effective treatments for addictions and to addicts seeking treatments for their habits. In short, legal prohibition fails to achieve its own supposed intention effectively, for consumption of the controlled substance is not significantly reduced and may even be increased over the long run.
Supply and Demand for an Addictive Product
