Last Sunday, the New York Times published an editorial that compared marijuana and alcohol use, particularly the relative harms of the two substances and the influence people substituting marijuana for alcohol could have on road safety.  But assuming the argument that alcohol and marijuana are “substitutes” bears out, that could be good news, especially for road safety. Of the two substances, alcohol is far more hazardous. For the most part, marijuana-intoxicated drivers show only modest impairments…