SEATTLE — A King County judge has ordered the state to reimburse Snohomish County the tens of thousands of dollars it spent complying with a 2017 law that requires more ballot drop boxes around the county.

And it must pay the other 38 counties, as well.

King County Superior Court Judge Nelson Lee ruled Oct. 14 that the law violated Washington’s unfunded mandate statute, which prohibits the state from requiring local governments to provide new or expanded service without giving them money to cover the cost.

Lee said all counties “shall be entitled to full reimbursement” for their “past and future reasonable costs expended” to comply with the law.

“The Court applauds the Washington State Legislature for taking affirmative and substantive steps towards increasing voter participation in elections,” he wrote. “That said, the counties should not be unduly forced to choose between full compliance and extreme economic hardship.”

The lawsuit, filed last December, centers on Senate Bill 5472, the 2017 law sponsored by former Republican state Sen. Kirk Pearson of Monroe. It requires that counties provide at least one drop box for every 15,000 registered voters and a minimum of one box in each city, town and census-designated place with a post office.

Snohomish County, a named plaintiff, has spent $155,000 so far. It has 30 drop boxes, 18 of which have been bought and installed since the law took effect.

The county is not done spending. With roughly 510,000 registered voters, it must add at least two more drop boxes to reach compliance. Election officials say the law creates an ongoing and ever-increasing mandate as county population grows.

“Snohomish County fully supports, and has worked diligently to implement, the 2017 legislation expanding access to ballot box locations,” County Prosecuting Attorney Adam Cornell said Thursday. “We are very pleased with the Court’s finding.”

Auditor Garth Fell said the county “always supported the expansion of ballot drop boxes,” and when the law passed, the county proactively invested to add more “because we recognized the benefit to our voters.”

“We are pleased that the Court commended Snohomish County on its significant investment and affirmed that when the State passes new legislation that imposes additional requirements on counties, the State bears the responsibility to provide the financial resources to implement those requirements,” Fell said.

State attorneys did not dispute that the law is “mandatory state legislation” but contended there are means for counties to seek reimbursement. And, they argued, a law set to take effect next year will give counties another avenue to recoup the cost of election operations in even-numbered years.

A trial to determine the amount the state must pay each county is set for April 19.

“Regardless of where you live, this case will have no impact on the availability or use of ballot boxes for the 2020 election,” reads a statement from the office of Attorney General Bob Ferguson. “The issue in the case is about who has to pay for the ballot boxes. We are consulting with our clients about next steps in the case.”

The Washington State Association of Counties is the lead plaintiff. The association, which represents the state’s 39 counties, hired Pacifica Law Group of Seattle to conduct the legal challenge.

Jerry Cornfield: 360-352-8623; jcornfield@heraldnet.com. Twitter: @dospueblos.