The City of Seattle, labor advocates, and Uber drivers hoping to unionize won a victory in King County Superior Court today.

There, Uber was suing over Seattle's first-in-the-nation law allowing drivers for companies like Uber and Lyft to vote to join unions and then collectively bargain with the rideshare companies. Specifically, Uber took issue with the process the city recently undertook to create the rules that will govern exactly how drivers unionize. Those rules included decisions like which drivers should be allowed to vote on whether to unionize, and Uber claimed the rules the city came up with are arbitrary and capricious.

King County Superior Court Judge Beth Andrus didn't buy Uber's argument today, ruling that the city's process was legal.

In a mostly empty courtroom today, lawyers for Uber and the city clashed over whether Seattle could adequately prove that its rules—particularly its decision about which drivers can vote on unionizing—fit with the intent of the law: to ensure drivers can work in "a safe, reliable, stable, cost-effective, and economically viable manner."

Uber has argued all drivers should get an equal vote. The Teamsters Union, which hopes to represent drivers, has said full-time drivers' votes should be weighted more heavily than drivers who only give a few rides a week. The city struck a middle ground, deciding drivers can vote on unionizing only if they've been with the company for the last three months and made at least 52 trips in Seattle during any three-month period in the last year.

Today, Uber lawyer Robert Maguire claimed the 52-trip cutoff had no real relation to safety or reliability and that the cutoff “disenfranchises thousands of drivers from having a critical voice in their working conditions." The city said the more often drivers are on the road, the more interest they have in the law. The city also took issue with Uber's lack of specificity on just how many drivers would or wouldn't be able to vote under the law. The company is notorious for refusing to hand over information it considers "trade secrets."

“You attempt to get information about all of this stuff from those being regulated and they refuse to give it to you," Assistant City Attorney Michael Ryan told the judge. "'Thousands'—is that 2,000, 9,000? We don’t know because they won’t tell us.”

(Labor lawyer Dmitri Iglitzin, representing the Teamsters, also pointed out the irony of Uber claiming to care about drivers being disenfranchised after the company has spent years arguing drivers aren't actually their employees.)

After more than an hour's worth of arguments from each side, Andrus sided with the city, though she said Uber's argument about whether the 52-ride cutoff really served the intent of the law was compelling. The city's process satisfied constitutional requirements, she said, "despite [the fact that] the court might have done it differently.”

Today's ruling is just a precursor to the bigger legal fights facing Seattle's Uber unionization law.

In federal court, about a dozen Uber and Lyft drivers have filed a lawsuit arguing the unionization law violates federal labor law and drivers’ First Amendment rights by "stripping them of their right to speak and contract with” rideshare companies. The Freedom Foundation and the anti-union National Right to Work Legal Defense Foundation are representing the drivers.

Meanwhile, the U.S. Chamber of Commerce is suing the city for the second time over the law, also arguing that it violates federal labor law. (Members of the Seattle City Council acknowledged the law is essentially a legal test case when they passed it; federal judge threw out the Chamber’s first lawsuit last year because the law had not yet taken effect.) The first hearing in that case is set for March 30.

That means that, while the law survived one legal challenge today, it's far from safe.

In a statement after the ruling today, Brooke Steger, general manager for Uber in the Pacific Northwest, doubled down on the company's arguments about the city's rules. "Seattle should be working to give drivers a voice rather than denying them one," Steger said. "We will continue to look for ways to raise these very serious concerns."

While the judge denied Uber's request today, she said the company did have the standing to challenge the city's rulemaking in court. That clears the way for Uber to appeal the case to the Washington State Court of Appeals, if they decide to. A spokesperson for the company did not answer a request for comment on whether Uber plans to appeal.