A driver can be held legally responsible, if that driver failed to act reasonably while operating the motor vehicle and therefore the driver has to compensate the victim for all injuries he or she causes. Failure to act reasonably is identified as someone who did not use the level of skill and caution a reasonably and careful person would use in a similar situation.
There are laws and regulations attached to almost every decision a driver makes while operating a motor vehicle. Negligence is determined based upon whether or not that decision violates the laws and regulations.
In the state of California, if both drivers involved in a vehicular accident are partly responsible for that accident, then each are the right to collect their share of damages.
The owner of the vehicle may also be held liable, if he or she loaned their car to the person responsible for that accident.
An employer may also be liable if their employee is held responsible for the accident, if that employee is operating within the capacity of their job.