Smoke Signals and Mixed Messages: Medical Marijuana & Drug Policy Signalling Effects

Liberal drug policy reform is often criticized for ‘sending the wrong message’, particularly to youth. Reform opponents argue that liberal policies such as decriminalisation and medical marijuana laws will cause marijuana to be perceived as less risky and lead to an increase in use. We seek to test this claim empirically, exploiting the timing and unique properties of state level medical marijuana laws in the US to isolate policy signalling effects. We use survey-derived state-level estimates of youths’ marijuana risk-perceptions and use prevalence, and find evidence of signalling effects on aggregate risk-perceptions of marijuana use that correspond to the introduction of medical marijuana laws. These effects, however, do not conform to what reform opponents predict - medical marijuana provisions appear to send the ‘right’ message. Further, we find no robust effects on nonmedical marijuana use.