Proposition 36 saved taxpayer dollars in the short-run, primarily because of avoided incarceration costs.
California taxpayers saved $2-$2.50 for every $1 spent on Proposition 36, largely attributable to avoided incarceration costs (Longshore et al., 2006; Hawken et al., 2008). This is based on a cost-benefit study comparing Proposition 36 referrals with a group that would have been eligible for the program if it had existed before implementation. The study focused on the costs associated with criminal justice, treatment, and health care. The Legislative Analysts Office (2000) projected that the passage of Proposition 36 would lead to a "one-time avoidance of $450 - $550 million in capital outlay for new prison construction"; however, it is impossible to prove that the prison would have been constructed had Proposition 36 been rejected.
Whether or not Proposition 36 saves taxpayers money in the long run is a vital question deserving of additional research. Future studies should also incorporate the victimization costs associated with the increase in property offenses as well as other costs and benefits (e.g., the costs associated with being incarcerated or having a family member incarcerated).
A report by the Arizona Supreme Court (2006) finds evidence that Proposition 200 has saved taxpayer funds as well. They report over $14 million was avoided in prison costs and almost $6 million was spent on probation and treatment services; however, a full cost-benefit analysis from the perspective of the taxpayer has not been conducted.