First, openly tolerating a market in a previously illegal commodity will expand the number of users, especially if the retail price is lower than the black-market price (as is proposed in the Ammiano Bill currently before the California legislature). Use may not increase immediately, but it will over time, because marijuana will become more freely available, much cheaper (in order to discourage the persistence of a black market), and its use will be implicitly condoned.
但即便无法借鉴别国经验，某些大概的情况还是可以推测出来的。首先，让某种非法产品在市场上公开交易的行为将增加该产品使用者的数量，尤其是在零售价低于黑市价之时（早前由加州议会议员阿米亚诺提交给州立法机关的大麻合法化法案也提到了这一点），大麻使用量不会在短期内急剧增加，但会随着时间增长，因为获得大麻不仅更容易，而且更廉价了（为了压倒黑市交易），而大麻的使用无疑也会得到其他人的认可。