Popular Science looks at the hard facts behind decriminalization and legalization (two different things!) of marijuana – and what science says happens when cannabis consumption is no longer a major crime:
What happens to states that decriminalize marijuana?
The best-known consequence to decriminalizing marijuana: The criminal-justice system saves money and resources. We’ve seen strong scientific backing on this because it’s a relatively easy outcome to measure.
Drug-related arrests and prison sentences decrease, which may fall in line with the majority American attitude that the government spends too much enforcing marijuana laws, anyway.
Exactly how much money will a state will save in prosecution costs? That’s under intense debate. Different studies of California have found savings ranging from hundreds of millions of dollars to more than a billion dollars–an unhelpfully big range.
Do people use marijuana more after their home state decriminalizes it?
No, or not much. Studies of use after decriminalization generally find either no effect or a small increase in use. Most recently, the American Academy of Pediatrics found that the rate of kids under age 18 who reported smoking marijuana doesn’t change after their home states pass laws allowing for medical marijuana. (If anything, those numbers decreased in many states–but chance alone best explains the perceived decrease.)
One possible reason decriminalization doesn’t have much of an effect is that people don’t actually seem to know whether they live in a decriminalized state….
How do decriminalization laws affect people’s health?
The public health effects of marijuana decriminalization are unclear.
In 1992, a RAND Corporation economist named Karyn Model published a study that found that in states which decriminalized the possession of marijuana in the 1970s, marijuana-related emergency room check-ins increased, while emergency visits for other drugs decreased.