Prohibiting the consumption of any good is always likely to have undesirable effects. One typically unintended consequence is the tendency for less costly varieties of the good to disappear in favor of expensive variants, which provide rewards to suppliers that better compensate for the legal risks inherent in their trade. Some have dubbed this the “Rhett Butler effect,” after the dashing blockade runner in Gone With The Wind. This effect is discussed in “Why Rhett Butler’s Weed Is So Strong“,:

“… in the context of the North’s blockades against the South, blockade runners could profit more from delivering smaller and lighter-weight luxuries to Confederate ports. The South thus found itself flush with things like ‘bonnet ribbon, playing cards, corset stays and . . . all kinds of personal items.’” 

In the context of alcohol prohibition and, more recently, the so-called war on drugs, prohibition has created a systematic tendency for the potency of contraband to increase. Art Carden quotes Milton Friedman on this point: “crack would never have existed…if you had not had drug prohibition.” The unfortunate result is that drugs become more powerful and often more dangerous and addicting. The cost also rises on average, which may create incentives for desperate users to engage in other nefarious activities.