A third potential mechanism underlying the association between medical marijuana laws and marijuana use and abuse/dependence is medical endorsement of its use for medical purposes. However, no consensus exists at this time on the effectiveness of marijuana as a treatment for symptoms of pain, nausea, vomiting and other problems caused by illnesses or treatment (Joy et al., 1999; MacCoun and Reuter, 2001a; Martín-Sánchez et al., 2009). The lack of medical consensus means that both pro and con proponents of medical marijuana laws can find research support for their positions, and the medical community has not delivered a clear message to the public.
