A King County Superior Court judge is hearing a challenge to the voter-approved $15 an hour minimum wage requirement for airport workers in SeaTac.
The court challenge is being led by Alaska Airlines Group and other business groups, which say the law should not apply at the airport, which is operated by the Port of Seattle.
The measure is set to take effect Jan. 1 after it survived a recount.
Opponents say the requirement will hurt business and reduce employment. Supporters say workers need higher pay as a matter of fairness.
Washington has the nation's highest state minimum wage at $9.19 an hour. The federal minimum wage is $7.25 an hour.
The judge is expected to give a bench ruling Friday, but whatever the outcome, an appeal is expected.