In California the owner of any dog is liable for the damages suffered by any person who is bitten by the dog while in a public place, or lawfully in a private place. The owner of the dog is liable even if the dog bites on the owner's property. It does not matter if the owner new the dog was vicious or not. A person is considered to be lawfully upon the private property when he is on the property in the performance of any duty imposed upon him by the laws of the State of California or by the laws or postal regulations of the United States, and also when the person on the private property on invitation from the property owner, the invitation could be expressed or implied.