A federal judge in Seattle on Tuesday temporarily blocked the city’s first-in-the-country law allowing drivers of ride-hailing companies such as Uber and Lyft to unionize over pay and working conditions.

US district judge Robert Lasnik’s ruling comes after he heard arguments last week in a case brought by the US Chamber of Commerce. He said his decision was not an indication of how he would ultimately rule.

“The issues raised in this litigation are novel, they are complex, and they reside at the intersection of national policies that have been decades in the making,” Lasnik wrote. “The public will be well-served by maintaining the status quo while the issues are given careful judicial consideration as to whether the city’s well-meaning ordinance can survive the scrutiny our laws require.”

The chamber sued to block the law before a deadline for the companies to provide information about their most active drivers to the Teamsters union, which has been selected to represent the drivers.

The lawsuit argues that federal law trumps the city’s statute. Seattle’s lawyers disagreed and said allowing drivers to bargain over their working conditions would make the industry safer and more reliable.

Seattle has been a national leader on workers’ rights, such as gradually raising the minimum wage to $15 and requiring most employers to provide paid sick leave. The legislation approved by the Seattle city council in late 2015 was seen as a test case for the changing 21st-century workforce.

It requires companies that hire or contract with drivers of taxis, for-hire transportation companies and app-based ride-hailing services to bargain with the drivers, if a majority shows they want to be represented.

Opponents of the law, such as Uber and Lyft, argued at the time that drivers were independent contractors and federal labor law prevented cities from regulating collective bargaining. They also said it would stifle the growth of the on-demand economy.

Mike O’Brien, the city councilman who proposed the law, has said that for-hire drivers are excluded from such protections as independent contractors. He saw the law as the next step in the fight for workers’ rights.