Cargo operations have been shut down in Oakland as truck drivers continue to protest a new California labor law they say prevents them from working for themselves, it was announced Wednesday. 

The protest began on Monday and involved hundreds of owner/operators who have been blocking the movement of cargo in and out of Oakland port terminals. As of Wednesday, there was no word as to when the protest might end. 

“The shutdown will further exacerbate the congestion of containers,” the port said in a statement. 

While the law making truckers employees instead of independent contractors was meant to protect them by making them eligible for benefits and minimum wage requirements, the truckers involved in the protest argue that the law could make it harder for those who own their own trucks to operate their own hours and be their own boss. 

The new law has not yet been enforced, and it is not yet clear when the state may begin enforcement, reported the Los Angeles Times.

“We understand the frustration expressed by the protesters at California ports,” Port of Oakland Executive Director Danny Wan said in the port’s statement. “But prolonged stoppage of port operations in California for any reason will damage all the businesses operating at the ports and cause California ports to further suffer market share losses to competing ports.”

The California Trucking Association has already sued over the law.