Can someone tell me what laws govern rental car companies in california ?

Also what is the minimum amount of third party lability that a rental company "must" cover in california without the renter having to buy additional insurance ?? Would appreciate links to the specific laws or good website !!

Most rental companies provide liability up to the state minimum limit of liability. So, what ever the state minimum is in CA - that's the amount the "must" provide and usually do provide.

However, the rental contract frequently says that any liability coverage they provide is excess to your liability insurance. That means, they pay only after your liability policy has paid it's limit.

If you do not have comprehensive or collision coverage on your car - you will have to purchase a damage waiver from the rental company.