This study analyzes data from 43 substance abuse treatment providers in California using the Drug Abuse Program Cost Analysis Instrument.  The study found that "on average, substance abuse treatment costs $1,583 and is associated with a monetary benefit to society of $11,487, representing a greater than 7:1 ratio of benefits to costs—or $7 in benefits every $1 spend on treatment."  The authors found that these benefits were primarily because of reduced costs of crime and increased employment earnings and concluded that, "even without considering the direct value to clients of improved health and quality of life, allocating taxpayer dollars to substance abuse treatment may be a wise investment."

Ettner, S. L., D. Huang, & Evans, E. et al. (2006). Benefit-cost in the California treatment outcome project: does substance abuse treatment "pay for itself"? Health Service Research, 41(1): 192-213. DOI: 10.1111/j.1475-6773.2005.00466.x http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16430607