A new study published in the American Journal of Public Health found little effect of adult-use marijuana laws on prevalence of marijuana use among youth.In this examination, researchers focused specifically on 504 justice system-involved adolescents in California, who, as they point out, have substantially higher marijuana use levels as compared to the general youth population. Among this population, they found marijuana use levels in the past 24 hours were similar in 2015 (before adult-use marijuana…