A used car dealership and two road-user industry groups are asking the Oregon Supreme Court to overturn a new 0.5 percent tax on the sale of new cars.

Oregon AAA, subsidiary AAA AutoSource and the Oregon Trucking Association argued in a Nov. 3 petition that the planned tax violates the Oregon Constitution, which puts strict limits on expenditures of road-related tax revenues.

The state fund that is used to pay for roads is separate from the fund that pays for other state services. Voters approved an amendment to the Oregon Constitution in 1980 that requires proceeds from vehicle-related taxes to go to the road fund and pay only for highway-related expenses.

But the tax set to take effect on car sales on Jan. 1 -- dubbed the "privilege tax" by lawmakers, because they say it's a tax on dealers for the privilege of selling cars -- won't work that way. Privilege tax revenues would go into a new separate spending account to subsidize purchases of electric vehicles. Legislative staffers estimated the tax will raise about $60 million per year.

Lawmakers created that account and the privilege tax to fill it when they passed House Bill 2017, a package to spent at least $5.3 billion on transportation and infrastructure projects. They also put into the bill a "poison pill" that allows the tax to be quickly thrown out by the Oregon Supreme Court, said Gregory Chaimov, attorney for the petitioners.

Chaimov said his clients don't have anything against road-related taxes. They just want the taxes to pay for road maintenance and upgrades, he said. Chaimov's clients argued that because privilege tax revenues go elsewhere, their bottom line suffers.

"That's the underlying issue," Chaimov said.

Attorney General Ellen Rosenblum's Oregon Department of Justice has yet to file an argument in response.

Sen. Brian Boquist, R-Dallas, provided emails to The Oregonian/OregonLive showing he has asked the Legislature's attorneys to consider filing a brief so the Legislature can clarify its intent on the privilege tax. Boquist is one of four lawmakers who played a key role in authoring this year's transportation package.

Court spokesman Phil Lemman said each side will likely be filing briefs for months before oral arguments. The case certainly will not be resolved before the end of the year, Lemman said. The privilege tax will take effect January 1.

-- Gordon R. Friedman

503-221-8209; @GordonRFriedman