Uber Technologies Inc. UBER, +3.32% and delivery startup Postmates filed a lawsuit Monday that seeks to declare unconstitutional a California law that could force the companies to consider their drivers as full-time employees instead of contractors. The two companies and two workers filed the suit in Los Angeles federal court on Monday seeking to halt Assembly Bill 5, which is set to become law on Jan. 1 after passing California's state legislature and being signed by Gov. Gavin Newsom this year. The challenge contends that the law is specifically targeted at "network companies" that connect those in need of a service and those who perform the service, which Uber claims to be. "This targeting of app-based workers and platforms and treating them disparately from traditional workers violates the Equal Protection Clauses of the United States and California Constitutions," the complaint contends. Uber has suggested that it will not begin classifying its drivers as employees instead of independent contractors when the law goes into effect, and that it would attempt to put a referendum on the 2020 ballot to exclude ride-hailing services like its own from the law.