Los Angeles (AFP) - Seattle has passed a measure allowing drivers of smartphone-based taxi companies like Uber and Lyft to unionize over pay and other working conditions, the first move of its kind in the United States.

The Pacific Northwest city’s council unanimously backed the bill. Mayor Ed Murray was quick to say he would not sign the measure, which can become law without his support.

The firms have fought such measures, arguing they offer more flexibility and pay than traditional companies to their drivers, who they consider independent contractors.

“This legislation is a huge victory for all the underpaid workers seeking to rebuild the labor movement and fight for a decent life,” said Council member Kshama Sawant.

“Massive corporations such as Uber, Lyft, FedEx and others exploit loopholes around independent contractors to try and prevent workers from unionizing.”

Under the ordinance, a majority of drivers paid to give rides will be given the option to join a union, and penalties will be applied for companies that fail to comply.

The measure applies to all such drivers, whether they are paid by a taxi company, a for-hire company or a so-called transportation network company like Uber that uses an online-enabled platform to connect drivers and passengers.

“I remain concerned that this ordinance, as passed by the Council, includes several flaws, especially related to the relatively unknown costs of administering the collective bargaining process and the burden of significant rulemaking the Council has placed on City staff,” said Murray.

“Since my concerns were not adequately addressed in this legislation, I will not sign this bill. Under the City Charter, the ordinance will become law without my signature.”