Seizing on a recent ruling by the California Supreme Court, San Francisco City Attorney Dennis Herrera on Tuesday issued subpoenas to Uber and Lyft for records related to whether their drivers should be classified as employees or independent contractors.

California’s high court late last month opened a new front in worker classification litigation when it set stricter standards for companies that label workers as contractors and not employees. Herrera said in a statement that the ruling “directly affects” San Francisco’s employment laws, including its minimum wage ordinance and health care requirements.