Negligence in an automobile accident usually is based upon a violation of the "rules of the road," which is the codification of a uniform law that regulates driving. The "rules of the road" are in Chapter 46.61 of the Revised Code of the State of Washington.

In addition to the driving rules that are established by statute, the appellate courts of the State of Washington have created what is known as "common law" based upon actual cases that have been tried and appealed. When an appellate court decides a case, it usually pronounces rules of behavior or duties that become law and which motorists must follow.

The liability that is imposed upon a driver in an accident is based upon a combination of the rules of the road and the state's common law. When a case is tried  before a jury, the judge instructs them precisely as to the duties of the motorist and the jury determines the facts. Examples of some common jury instruction are as follows: