Local tribes could lose the ability to use their gas tax exemption for non-highway purposes after a state Supreme Court ruling last week. A group of non-tribal gas station owners had sued the state challenging the tribal gas tax exemption. Michael Ennis with the Washington Policy Center says the group claimed that tribal stations were using their 75-percent tax refund to undercut gas prices. The exemption currently allows tribes to spend the money on non-highway purposes, which Ennis says is a violation of the state constitution. The state claimed that tribes had sovereign immunity on the issue, but the Supreme Court rejected that argument. The case will now go back to the trial court.