Context: The Mental Health Parity and Addiction Equity Act (MHPAEA) requires coverage for mental health and substance use disorder (MH/SUD) benefits be no more restrictive than for medical/surgical benefits in commercial health plans. State insurance departments oversee enforcement for certain plans. Insufficient enforcement is one potential source of continued MH/SUD treatment gaps among commercial insurance enrollees. This study explored state-level factors that may drive enforcement variation.

Methods: We conducted a four-state multiple-case study to explore factors influencing state insurance offices’ enforcement of MHPAEA. We interviewed Twenty-one individuals representing state government offices, advocacy organizations, professional organizations and a national insurer. Our analysis included a within-case content analysis and a cross-case framework analysis.

Findings: Common themes included insurance office relationships with other stakeholders, policy complexity, and political priority. Relationships between insurance offices and other stakeholders varied between states. MHPAEA complexity posed challenges for interpretation and application. Policy champions influenced enforcement via priorities of insurance commissioners, governors, and legislatures. Where enforcement of MHPAEA was not prioritized by any actors, there was minimal state enforcement.

Conclusions: Within a state, enforcement of MHPAEA is influenced by insurance office relationships, legal interpretation, and political priorities. These unique state factors present significant challenges to uniform enforcement.

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