Rental Liability coverage is required in the state of CA. You must either provide written proof of coverage or purchase. Liability coverage does not cover your rental car, it covers any damage that your vehicle would cause to any 3rd party property. Liability coverage provides third party liability protection for bodily injury ($15,000 per person, $30,000 per accident) and property damage ($5,000) to third parties, as mandated and at the limits required by California.