But Trudeau's argument for legalization is concerned less with creating benefits, and more with reducing harms. He starts from the same place that many legalization opponents start from — concern for the safety of children.
Opponents of legalization have always argued that relaxing marijuana laws will inevitably lead to increased use among teens and adolescents. This would obviously be a problem, because younger users are more at risk for marijuana dependency than adults, and heavy use among teens has been linked to a whole host of social and mental health problems.
But Trudeau points to an easy-to-overlook fact: It's already incredibly easy for teenagers to get high if they want to. In 2015, for instance, nearly 80 percent of U.S. 12th-graders said it would be easy for them to obtain marijuana. It's clear, in other words, that current policies centered on making the drug completely illegal are doing little to keep it out of the hands of kids who want to use it.
Trudeau argues that taking pot out of the black market and putting it under the aegis of a regulatory structure will actually make it harder for kids — those most susceptible to the drug's harms — to obtain it. We don't really know yet if that's the case. Legalization experiments in Colorado and elsewhere are still too young to draw sweeping conclusions about the effects of legalization on teen use and access.
That said, the early data is encouraging. A recent study published in Lancet Psychiatry found that the over the past decade or so — as 13 states passed medical-marijuana laws, 10 states relaxed penalties for marijuana use, and Colorado and Washington became the first states to fully legalize recreational pot use — not only have national teen marijuana use rates declined, but problems associated with teen marijuana use, like dependency, have fallen too.
Beyond that, the latest federal data shows no significant year-over-year change in marijuana use among teens in Colorado and Washington in the year after marijuana became legal there.
Experts say none of this is particularly surprising. "Most of the legal changes have pertained only to those 21 and over, so the absence of a big increase in teens is exactly what you’d expect," Jonathan Caulkins of Carnegie Mellon University told me late last year.
In short, it may be the case that marijuana legalization will have a much smaller impact on teen use rates than once feared. This doesn't mean that legalization doesn't bring risks of its own, however. If marijuana is more widely available, more people will use it, and a certain percent of them will develop a dependency on the drug. And another subset of users will end up doing incredibly stupid or dangerous things while high.
But the question is weighing these very real risks of harm against the harms that are already occurring because of prohibition. Marijuana prohibition ruins lives — lives of the hundreds of thousands of people arrested for possessing the drug each year, or the lives of thousands of people put behind bars for years on account of simple marijuana possession, or the lives of people living in the communities wracked by violence when rival drug gangs fight over turf and put innocents in the crossfire.
Trudeau is saying that this current approach isn't working, and that people legitimately concerned over the harms of the drug trade should consider a radically different approach. So far, the evidence is backing him up.