The debate over the legalisation of cannabis tends to focus on what adults should or shouldn’t be allowed to do with their own bodies. Less attention is paid to children – indeed, the unspoken assumption appears to be that even if cannabis is legalised, its sale to under-18s would remain illegal. Certainly, this would be consistent with the law on selling alcohol and tobacco to minors.

The issue does present a rather awkward dilemma for the liberalisers. One of their key arguments is that it’s not so much the drug that does the harm, but the consequences of prohibition. If that’s true, then wouldn’t decriminalisation with an age limit concentrate the harmful effects on children? After all, there’s only three things that existing dealers could do in such a situation – give up, go legit or specialise in the youth market.

Not having an age limit though, is unthinkable: we’d have to accept the open sale of cannabis to the age group most vulnerable to its impact on brain development and mental health. Or do the legalisers envisage some sort of state monopoly – with little bags of regulation-strength pot dished out to school kids with their free condoms?

Before allowing cannabis to circulate freely in the adult population we have to ask what effect this would have on its availability to children. In the New York Times, Jack Healy reports from Colorado, a state which has legalised the sale of cannabis for medical, and now recreational, use. He begins by describing the remarkable diversification of the industry:

“…marijuana-infused snacks have become a booming business, with varieties ranging from chocolate-peppermint Mile High Bars to peanut butter candies infused with hash oil.

“Retail shops see them as a nonthreatening way into the shallow end of the marijuana pool, ideal for older customers, tourists staying in smoke-free hotels or anyone who wants the effect without the smoke and coughing…

“So far, the state has given licenses to 34 ‘retail marijuana product manufacturers,’ who extract THC-rich oil from marijuana plants to make everything from lip balm and lotion to chocolate candies.”

Well, that sounds like fun – until, that is, one considers the unintended consequences:

“…the popularity of edible marijuana has alarmed parents’ groups, schools and some doctors, who say the highly concentrated snacks are increasingly landing in the hands of teenagers looking for a sweet, discreet high, or of children too young to know the difference between pot brownies and regular ones…”

“One survey has found a small but growing number of children seeking treatment after accidentally consuming marijuana. Fourteen such children visited the emergency department of Children’s Hospital Colorado in the Denver area from October 2009 through December 2011, researchers reported last year in the journal JAMA Pediatrics. Before 2009, researchers reported no marijuana exposures.”

It should be said that the legal age limit for the sale and use of cannabis in Colorado is 21. Furthermore, there are additional regulations designed to prevent its accidental or intentional use by minors – such as the mandatory labelling of ingredients.

If such safeguards don’t work should we be surprised? Anti-prohibitionists argue that the full force of the law is powerless before the irresistible demand for drugs (or, for that matter, prostitution). It is therefore odd that they should have such confidence in the power of petty regulation to contain the impact of legalisation.