Washington Supreme Court Invalidates Natural Gas Initiative, Rejecting Attempt to Roll Back Washington Climate Legislation at the Ballot Box

Summary

On September 17, 2026, the Washington Supreme Court invalidated as unconstitutional Initiative 2066 (I-2066), which sought to repeal a range of climate legislation adopted by the Washington Legislature that sought to discourage the use of natural gas as part of the state’s transition to energy sources that do not emit greenhouse gases. The decision, Climate Solution et al. v. State of Washington, removes a cloud of uncertainty over Washington’s climate legislation, at least as it relates to the phase-out of natural gas. Businesses using, selling, or distributing natural gas in the state will now need to comply with legislative mandates aimed at phasing out Washington’s reliance on fossil fuels in the next few decades.

Key Takeaways

• I-2066 sought to preserve businesses' and consumers’ ability to continue using natural gas. The initiative’s invalidation means businesses and consumers that use natural gas, or are otherwise involved in the natural gas industry, now face statutory mandates to phase out natural gas use in Washington.

• The initiative targeted a range of legislation addressing natural gas use in Washington. I-2066 aimed to broadly prohibit all local governments and some utilities from taking measures to discourage or bar natural gas use, inhibited air quality regulators from taking measures that would discourage use of natural gas, amended the Washington Decarbonization Act for Large Combination utilities to remove certain decarbonization requirements, and to prevent the state building council from adopting Building Code provisions that would discourage gas usage or to promote the transition away from fossil fuels.
• The initiative’s broad range proved to be its undoing. A six-justice majority of the Supreme Court concluded that the initiative violated the Washington Constitution’s requirement that legislation address only a single subject.

Background

In the years leading up to the 2024 election, the Washington Legislature and regulators enacted several ambitious measures to address climate change. As relevant here, in 2019, the Legislature enacted the Clean Building Performance Standards, which aims to reduce the carbon intensity of buildings in the state, including through measures discouraging the use of fossil fuels for heating and cooling, and encouraging a transition to electrification for these functions. In 2021, the Legislature enacted the Climate Commitment Act, which establishes a declining statewide cap on greenhouse gas emissions and a cap-and-trade program applicable to all sources in the state emitting more than 25,000 tons of GHGs per year.

In 2024, the Legislature enacted the Decarbonization Act for Large Combination Utilities, which was aimed primarily at addressing the complications of decarbonization for large utilities that provide both natural gas and electricity to retail consumers. That legislation required such utilities to encourage building electrification and to identify and carry out least-cost decarbonization pathways identified in their integrated resource plans. The 2024 Legislature also enacted changes to the statutes governing the Washington State Building Code to encourage the adoption of code provisions discouraging the use of natural gas for heating and cooling in new buildings, strengthening the earlier-adopted goal of eliminating new buildings that use fossil fuels by 2031.

Let’s Go Washington, a political action committee, launched successful petition drives to place four initiatives on the 2024 general election ballot. These included I-2117, which would have repealed the Climate Commitment Act, and I-2066, which aimed to defeat various statutes restricting or discouraging the use of natural gas as a means of addressing climate change.

I-2117 was soundly defeated at the polls, but I-2066 passed with a majority of about 51.7%. A coalition composed of King County, the City of Seattle, several environmental and social justice organizations, the Washington Solar Energy Industries Association, and green home developer Dwell Development sued to block the initiative, arguing that it violated several provisions of the Washington Constitution governing the adoption of legislation, including initiatives. The King County Superior Court agreed, invalidating I-2066.

The Washington Supreme Court agreed to direct review of the Superior Court’s decision and, on September 17, issued an opinion upholding the Superior Court’s order invalidating I-2066. A six-justice majority concluded that the initiative addressed multiple subjects, and therefore violated Article II, Section 19 of the Washington Constitution, which requires that “[n]o bill,” including any initiative, “shall embrace more than one subject.”

Conclusion

The Supreme Court’s decision invalidating I-2066 strikes from Washington statutes those provisions of I-2066 that would have restricted state and local government agencies from restricting or discouraging the use of natural gas. Similarly, the provisions that would have repealed provisions of the Decarbonization Act aimed at phasing out the use of natural gas by Washington’s large gas/electric utilities and encouraging building electrification, and provisions that would have limited building code provisions aimed at eliminating new buildings using fossil fuels are now gone. Utilities, building owners, the natural gas industry, and end-use consumers of natural gas should now expect the Legislature and Washington regulators to move forward with the decarbonization agenda, including measures to phase out the use of natural gas in the state and to broadly encourage the electrification of buildings and industrial processes.

Beveridge & Diamond is a national leader in climate and energy matters, regularly representing energy developers, utilities, and large industrial consumers in litigation, regulatory, and transactional matters. With an office in Seattle, our Electric Power, Pipelines, and Renewable Energy practices provide comprehensive environmental regulatory, litigation, and transactional support to clients with operations across the country, including Washington.