Signal Washington Supreme Court strikes down natural gas initiative as unconstitutional

Summary

The Washington Supreme Court ruled 6-3 on September 17, 2026 that Initiative 2066, approved by roughly two million voters in 2024, is unconstitutional in its entirety. The initiative was designed to protect natural gas access and roll back state energy-efficiency and building-decarbonization efforts. The majority opinion found the measure violated the state constitution's single-subject rule by bundling four distinct regulatory changes: regulating natural gas providers, undermining air-quality protections, removing zero-emission and building-efficiency goals, and amending the state's Decarbonization Act. The court held that no individual provision could be severed and saved, so the entire initiative was void. A King County Superior Court judge had already ruled the initiative unconstitutional on the same grounds in March 2025; the Supreme Court's decision affirms and finalizes that ruling.