Determining fault in a car accident is a matter of figuring our the degree to which each driver involved caused the accident. Determining fault is done according to state law where the accident took place. Each state's rules vary, and so the best option is to contact a local car accident attorney for the rules in your state.

States are divided into two main categories of how they deal with fault in automobile accidents, although there is significant variation within the categories. Most states are fault states. This means they have a tort liability system of auto insurance. This means that the driver who caused the accident, or his insurance company, is responsible for all damages to other parties involved in the accident. This may seem like a fair way to handle it, but it has the unintended consequence of clogging the legal system with accident claims. After all, if an at-fault driver denies he was at fault(and why wouldn't he?) there is no other avenue besides court to force him or his insurance company to pay.

In response to the massive legal costs of determining fault, some states have shifted to a no-fault system of auto insurance for handling accidents. There are currently twelve states with no-fault systems: Florida, Hawaii, Kansas, Kentucky, Massachusetts, Michigan, Minnesota, New Jersey, New York, North Dakota, Pennsylvania, and Utah. In these states they have eliminated many of the long and costly court battles that plague fault states.

In no-fault states, drivers to do not have to prove that someone else caused the accident in order to be reimbursed for costs from their insurance company. His insurance company usually pays all medical bills automatically. These states require minimum levels of personal injury insurance, shifting the cost of medical damages from the insurance company of the at-fault driver to the insurance company of the injured party. The trade off is that injured drivers cannot sue for pain or inconvenience damages unless his or her medical bills cross a certain threshold or the injury is deemed "severe" by state law. Damage to the car and other property, however, is still based on fault.