War on Drugs: just another Prohibition that only exacerbates the problem

Modern corporations have simply done away with the need for Prohibition on this front. Since drug and alcohol screenings provide a means of discriminating against irresponsible employees who would otherwise come to work drunk or high (especially in jobs where negligence can entail high costs in the form of ruined machinery and insurance payouts), employees take responsibility for their own decisions. Those who wish to exercise bad decisions, drink to excess, smoke occasional joints, call out for "sickness," and show up to work with hangovers may just as well seek employment in unskilled jobs under less discriminating employers (perhaps also losing insurance coverage in the meanwhile). The market tends to self-regulate and establish its own work ethic independent of state oversight. Prohibition — of any market phenomenon — only tends to exacerbate the so-called "problem."
Morgan A. Brown, Mises Daily