Expansion of Involuntary Treatment for Mental Illness and Substance Use Disorder: Experience With California's Senate Bill 43.

The United States is struggling with the intersecting crises of substance use disorder (SUD), mental illness, and homelessness. In 2023, California expanded involuntary treatments to address these issues, including adding SUD as a qualifying diagnosis. We present experience with California's revised law and review challenges affecting its implementation. Involuntary treatment of SUD lacks high-quality evidence and remains controversial. Although the revised law expands the criteria for involuntary treatment, its impact has been limited by bottlenecks in an overburdened system. To maximize the benefit of this law while minimizing attendant harms, we recommend using the least restrictive means possible, avoiding divestment from voluntary treatments, employing evidence-based interventions, improving transitions to community-based care, understanding bottlenecks for involuntary treatment, and promoting collaboration across specialties. (Am J Public Health. Published online ahead of print July 30, 2026:e1-e8. https://doi.org/10.2105/AJPH.2026.308584).