As more states make recreational marijuana legal, there is evidence that legalization leads to more usage.
According to a study released last week in the journal Addiction, people born in states where cannabis was made legal were 24% more likely to use cannabis after legalization.
The study also examined 111 sets of identical twins. Most sets of twins included one person who lived in a state where cannabis is legal and the other twin living somewhere it is not. The study found that an identical twin who lived in a state with legalized marijuana was 20% more likely to use it.
While the study gives strong evidence that legalization leads to higher usage, there might be some caveats.
“One potential alternative explanation for increases in use associated with legalization could be that it instead reflects an increased openness to report activities that are no longer illegal. We cannot determine whether this is the case, but we note that we also saw increases in reported cannabis use by residents of illegal states,” the authors wrote.
Although marijuana possession is now legal in states such as Colorado, it remains a crime at the federal level.