On the day Uber drivers in Seattle were set to get the right to unionize, the multi-billion-dollar ridesharing company is suing the city to try to stop that new law from taking effect.

The Seattle City Council passed an unprecedented law in 2015 allowing rideshare drivers who work for companies like Uber and Lyft to unionize. City departments have spent the last year trying to craft rules for how that law should take effect, including which drivers should be allowed to vote on whether to unionize.

Now, Uber—which has continually opposed unionization here in Seattle—claims that process was "arbitrary," "capricious," and "piecemeal," and "denied the public a meaningful opportunity to comment."

Among the many questions about how the unionization law would take effect was one particularly controversial one: Which drivers should get to vote on whether to unionize? While 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. Public hearings on the issue exposed a deep split among drivers.

Supporters of the unionization ordinance have cited stories from drivers who say they make less than $5 an hour on the app and drivers who say they have been unexpectedly deactivated, making them unable to work. They emphasize the stories of drivers who depend on the app for their livelihood, especially immigrants and refugees. Uber, meanwhile, has characterized stories of low pay or unexplained deactivations as outliers, pointing to drivers who say they can easily make $15 to $20 an hour. However, the company is notoriously stingy with its data, making it hard to know exactly how often the average Uber driver is working or what they're making. In its petition to the court today, Uber offers a small glimpse at the makeup of its drivers in Seattle. The company claims that more than half of Seattle drivers use the app less that 12 hours a week.

As the city proceeded on rule-making for the ordinance last fall, Uber began an advertising and organizing campaign to convince drivers they shouldn't unionize, warning them a union contract could limit when drivers can work or that new rules could cause Uber to leave Seattle. Union backers have disputed those claims, saying drivers would have the right to vote on any contract governing their working conditions, meaning they could reject a contract that threatened their job flexibility.

The city's Finance and Administrative Services Department (FAS) released the final version of the rules in late December. Those rules would allow drivers to vote if they've been with the company for the last three months and have made at least 52 trips in Seattle during any three-month period in the last year. The rules take effect today.

In its petition to King County Superior Court, Uber claims the rules "disregard the facts and circumstances of the for-hire transportation industry" and are "inconsistent" with current labor law. Uber calls the decision on which drivers should be allowed to vote "arbitrary" and argues it excludes "thousands" of drivers from voting. The company also takes issue with the survey data the city used to make that decision, saying only 10 percent of drivers or fewer responded. (The filing lists Rasier LLC, not Uber, as the petitioner. Rasier is a wholly owned subsidiary of Uber.)

The company claims that a majority of the feedback offered to the city on the draft rules was in favor of allowing all drivers to vote but that the city ignored that feedback. "This willful disregard of the facts after conducting a hasty process addressing an incomplete set of rules is the very definition of arbitrary and capricious," the company writes.

In the petition, the company asks the court to immediately halt implementation of the rules and declare them invalid.

Last year, the U.S. Chamber of Commerce also tried to stop the unionization law with a lawsuit, but failed.

Dawn Gearhart, the Teamsters Union's main organizer for this issue, was not available to comment on Uber's suit. Representatives for FAS directed questions to the Seattle City Attorney's office, and a staffer for Council Member Mike O'Brien, who sponsored the ordinance in 2015, said he would not comment until after he spoke to the city attorney's office.

A spokesperson for the city attorney's office told The Stranger by email Tuesday they had just received the filing. "All we will say now," she wrote, "is that our office will vigorously defend FAS's rulemaking."