The consequences of legal access to medical marijuana for individuals' well-being are controversially assessed. We contribute to the discussion by evaluating the impact of the introduction of medical marijuana laws across US states on self-reported mental health considering different motives for cannabis consumption. Our analysis is based on BRFSS survey data from close to eight million respondents between 1993 and 2018 that we combine with information from the NSDUH to estimate individual consumption propensities. We find that eased access to marijuana through medical marijuana laws reduce the reported number of days with poor mental health for individuals with a high propensity to consume marijuana for medical purposes and for those individuals who likely suffer from frequent pain.

This article comments on the role of empirical subjective wellbeing research in public policy within a constitutional, procedural perspective of government and state. It rejects the idea that, based on the promises of the measurement, we should adopt a new policy perspective that is oriented toward a decision rule maximizing some aggregate measure of subjective wellbeing. This social engineering perspective, implicit in much reasoning about wellbeing policy, neglects: (1) important motivation problems on the part of government actors, such as incentives to manipulate indicators, but also on the part of citizens to truthfully report their wellbeing; and (2) procedural utility as a source of wellbeing. Instead, wellbeing research should be oriented toward gaining insights that improve the diagnoses of societal problems and help us to evaluate alternative institutional arrangements in order to address them, both as inputs into the democratic process.