The most expensive ballot measure in California history centers around a much-litigated issue involving Uber and other app-based ride-hailing firms: Should their drivers be employees or independent contractors?

Uber, Lyft, DoorDash, Postmates and other firms have pumped about $200 million into Proposition 22, which goes before California voters Nov. 3. The measure exempts their drivers, increasingly used to deliver groceries and meals to homes during the COVID-19 pandemic, from a California law that classifies them as employees entitled to certain benefits. The firms insist that the measure would prevent the increased consumer costs predicted from the law, and that the majority of their drivers would prefer to be independent contractors with flexible schedules.