On Sept. 17, the Washington Supreme Court struck down Initiative 2066, the 2024 measure protecting residents' access to natural gas. The reasoning in that 6-3 decision, written by Chief Justice Debra Stephens over a dissent from Justice Sal Mungia, ruled that I-2066 violated the state constitution's single-subject clause, which bars initiatives (and bills) from combining unrelated policies into a single up-or-down vote. That rule doesn't just bind the initiative process, it binds the Legislature too. If the justices eventually uphold the state's new income tax, they'll have to explain why lawmakers get a pass on a rule they just enforced against voters.
The income tax enacted under ESSB 6346 already openly defies nearly a century of Washington Supreme Court constitutional precedent. Under a series of decisions running back to the 1933 Culliton ruling, income counts as property under the state constitution. That means any income tax must clear two hurdles: a 1% cap on property taxes, and the requirement that property in the same class be taxed uniformly. ESSB 6346 imposes a 9.9% tax on income over $1 million while exempting everything below it, a plain conflict with both rules and already under challenge in court.
Last week’s I-2066 ruling has the new income tax facing a second, independent argument: logrolling.
ESSB 6346 is not just an income tax bill after all. Lawmakers folded in changes to the business and occupation tax, adjustments to the sales tax, an expansion of the Working Families Tax Credit (WFTC), and a contribution to an early learning account, then sent the entire package out to a single vote. In the bill's legislative findings, lawmakers explicitly framed the income tax and accompanying relief as an "integrated reform." But a legislator who wanted to expand the tax credit, and opposed a new income tax, had no opportunity to vote for one without the other even though those are completely distinct policy choices. Under the single-subject rule the Supreme Court just reaffirmed four days ago, these policies belonged in separate bills, standing or falling on their own terms. The court has repeatedly rejected the idea that policies belong in the same measure just because they concern taxes.
Washington courts have enforced this single-subject rule against tax legislation for more than 70 years. In 1951, the court struck down a corporate income tax because it was tied to general state spending. In 2001, it struck down Initiative 722 for combining tax refunds with property assessment changes. In 2020, it struck down Initiative 976's vehicle-tax limit because transit bond provisions had been tagged on.
The Washington Supreme Court cited both the 2001 and 2020 rulings in throwing out I-2066. The pro-tax majority in the Legislature calling ESSB 6346 a "tax-reform package" doesn't grant them an exemption from following the law. If the court applied its rulings consistently, its own standard requires striking down the income tax as well.
Critics continue to second-guess why I-645 targets the income tax alone while leaving the accompanying tax relief and expansion of the WFTC untouched. One possibility is that broadening the initiative's scope to overturn the whole bill would have created a multi-subject measure, handing opponents like the public sector unions, who stand to gain the most from additional government spending, the exact same single-subject argument the court just wielded against I-2066. I do not trust a progressive court to give an income tax repeal initiative the benefit of the doubt, and the natural gas decision reinforces that concern. Keeping I-645 focused was a sensible way to protect the repeal effort and leave the remaining tax policy decisions to the Legislature.
The Seattle Times editorial board has turned that drafting choice into an argument against I-645. The board claims that leaving the relief provisions in place "locks them in" and "would prevent legislators from altering any of the initiative’s impacts for two years, absent a supermajority vote." They are incorrect. While Washington’s Constitution generally requires a two-thirds legislative vote to amend a voter-approved law during its first two years, leaving an existing law untouched does not turn that law into a new voter mandate. I-645 simply asks voters to ban an income tax, not to guarantee every other provision lawmakers attached to the flawed income tax bill.
A 1988 attorney general opinion also established that the two-year constitutional restriction applies only when later legislation alters an initiative's "essential purpose and effect." Tweaking a sales tax exemption or adjusting the Working Families Tax Credit doesn't undo a ban on income taxes, which is what I-645 does.
Because that two-year restriction doesn't apply to provisions the initiative leaves untouched, lawmakers would have immediate freedom during the 2027 and 2028 legislative sessions to amend, delay, or repeal the tax relief on a simple majority vote.
But even if we accept the editorial board’s flawed premise where the two-year supermajority requirement did apply, their argument still falls apart. The constitutional two-year window would expire on Dec. 3, 2028, while the tax relief itself doesn't even take effect until Jan. 1, 2029. That means the two-year restriction expires before the relief even kicks in. Any way you look at it, the editorial board is wrong. If lawmakers decide to roll back that tax relief or cut those credits, they will have to make that tough decision openly and defend it on its own merits.
Whether the Washington Supreme Court strikes down ESSB 6346 under the single-subject rule it just reaffirmed, or voters approve Initiative 645 this November to repeal the income tax, the outcome should be the same: the state’s unconstitutional income tax must go. Lawmakers cannot demand strict single-subject compliance from voters while exempting their own tax packages from the exact same constitutional standard.
