A King County Superior Court judge declined Friday to immediately rule on a challenge to the voter-approved $15 an hour minimum wage requirement for airport workers in Seattle-Tacoma International Airport.

Judge Andrea Darvas said she'll issue a ruling with reasoning after Christmas Day but before January 1. Parties in the case had been expecting a ruling Friday.

The measure is scheduled to go into effect on January 1.

Last month voters in the city of SeaTac narrowly approved the measure, which would require a $15 minimum wage, a handful of paid sick days and other standards to around 6,000 workers at the airport and related industries, like hotels and rental car companies.

However, the legal fight over the measure is not expected to end with Darvas' ruling. An eventual appeal to the state Supreme Court could come from either side, depending on her ruling.

The challenge to the newly approved measure is being led by Alaska Airlines Group and other businesses. They say that an initiative approved by city residents doesn't have power over the airport, which is operated by the Port of Seattle. The Port of Seattle, a public entity, agrees.

Alaska Airlines Group also says state law prohibits initiatives from packaging laws. So they're arguing that the multiple requirements in the measure, such as the minimum wage and paid sick days, constitute packaging multiple laws into one initiative.