Legal availability increases use, and the harm scales with the using population

The argument

Opponents of legalisation begin from price and access. Prohibition raises what a drug costs, limits where it can be obtained, and requires a buyer to find someone willing to break the law to supply it. Legalisation removes all three. Opponents argue that demand for drugs responds to availability much as demand for other goods does, so a legal market would mean more people using, heavier use among those already using, and earlier first use among the young, for whom the difficulty of obtaining a substance is often the operative obstacle. The harms at issue scale with that population. Dependence, impairment at work and on the roads, and overdose are all functions of how much is consumed by how many, so a policy that increases consumption can increase total harm even where each individual dose becomes safer. Opponents argue that supporters of legalisation count the gain in dose safety and leave the change in volume out of the comparison. They also argue that the regulatory answer is weaker than it looks. The substances already legal are the ones on which regulation has been tried longest, and in both cases a licensed industry has grown that draws the bulk of its revenue from its heaviest users and markets accordingly, while the state acquires a revenue interest that works against restriction. Opponents argue there is no reason to expect a legal drug industry to behave differently, and that the costs would again fall partly on people who never chose the risk: employers, road users, emergency services and the children of dependent parents.

Premises

Counter-arguments

Supporters of legalisation reply that the predicted surge in use is asserted rather than demonstrated, and that where possession has been decriminalised or particular drugs brought into a regulated market, consumption has not risen in the way opponents forecast. They add that the argument credits prohibition with suppressing demand while declining to count what the suppression costs, and that comparing a regulated market against an idealised abstinence, rather than against the unregulated market that actually exists, sets the baseline in the wrong place.

Rejecting the premises

[Rejecting P1] The responsiveness of use to price and access is assumed rather than estimated, and the argument needs it to be large. Where possession has been decriminalised or particular drugs brought into a regulated market, the increases have generally been smaller than forecast, which the premise does not accommodate. [Rejecting P2] That harm scales with consumption treats all use as harmful in proportion to its volume, when most of the harm is concentrated in dependent use. A rise in occasional use among people who do not become dependent need not raise total harm at all. [Rejecting P3] The comparison with alcohol and tobacco is apt and cuts both ways, since both are cases in which regulation has reduced harm substantially over time through taxation, advertising restriction and licensing. The premise reads those industries' conduct as evidence against regulation while omitting what regulation has achieved against them.