relative to involuntary admissions for certain individuals with a substance use disorder.

HB 1790 expands the definition of "mental illness" under New Hampshire law to include impairment primarily caused by substance use disorder (SUD) for involuntary admission purposes. This means individuals with SUD who meet specific danger criteria (such as extreme abnormal behavior or faulty perceptions) could now be subject to involuntary emergency or non-emergency admissions, similar to those with other mental health conditions. The bill explicitly excludes impairment from alcohol dependence, intoxication, epilepsy, or intellectual disability from this expanded definition. It directly affects people with SUD who pose a danger to themselves or others, requiring clinical evaluations and court processes under revised standards. The law takes effect January 1, 2027, with potential impacts on healthcare resources and admission systems.