In 2014, California voters approved Proposition 47, which reclassified drug possession offenses from felonies or “wobblers”—which prosecutors can charge as either felonies or misdemeanors—to misdemeanors, and in the process reduced the state’s prison and jail populations. Now, a study out of UC San Francisco has quantified the effects of the ballot measure, which was at the leading edge of a national movement to reduce incarceration rates and change the criminal justice approach to substance use disorders.