A month after voters supported the creation of a $15 minimum wage for hospitality and transportation workers in SeaTac, lawyers for all sides appeared in a Kent courtroom on Friday in an effort to sustain or shoot down the new law before it takes effect on Jan. 1.

The Nov. 5 ballot measure called for an hourly minimum wage of $15 for thousands of hospitality and transportation workers. The statute remains in limbo because of the court challenge by Alaska Airlines and the Washington Restaurant Association.

King County Superior Court Judge Andrea Darvas allowed each side to argue their case Friday. Darvas took notes and asked a steady stream of questions from many of the nine lawyers seated before her.

At the end of Friday’s hearing, Darvas said the case is complex and that she needs time to decide whether to uphold the law or strike it down. She said she’ll announce her decision by Jan. 1.

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It’s expected that the legal fight won’t end in county court. An eventual appeal to the state Supreme Court could come from either side, depending on the ruling.

While lawyers for Alaska Airlines and the Washington Restaurant Association appeared in court in opposition of the ordinance, lawyers for the city of SeaTac and SeaTac Committee for Good Jobs, the pro-Proposition 1 group, spoke out in support of it.

An attorney representing the Port of Seattle said the Port takes no official position on the $15 minimum wage, but explained how it would affect operations at the airport.

The measure, if left to stand, would undermine not just the Port’s exclusive jurisdiction to regulate businesses operating at the airport, but all facets of airport operation, at every airport in the state, according to the Port’s brief that was filed on Thursday.

Herman Wacker, an attorney for Alaska Airlines, argued that the measure violates federal laws and the U.S. Constitution. Opponents say that a city initiative doesn’t have power over the airport, which is operated by the Port of Seattle, and that requirements the measure sets violate the law that says initiatives can’t package multiple laws.

“There is no statute in America like this,” Wacker said. “This is not about whether $15 is a good idea or a bad idea.”

Supporters dismissed the business group’s court arguments, saying cities, not ports, enact social-welfare laws.

The initiative raises the city’s hourly-wage floor for hospitality and transportation workers to $15 from the statewide standard of $9.32 on Jan. 1 and assures annual inflation adjustments.

In addition to a $15 minimum wage, Proposition 1 requires affected employers to provide paid sick leave, promote part-time workers to full-time before hiring additional part-timers and retain employees for at least 90 days after an ownership change. Those requirements can be waived in a union contract.

Proponents of the measure say it will ease poverty and stimulate consumer spending, boosting the economy. Opponents say it will force businesses to raise prices and cut staff, hurting the economy.

Information from The Associated Press is included in this report.

Jennifer Sullivan: 206-464-8294 or jensullivan@seattletimes.com. On Twitter @SeattleSullivan.