In a car crash or other incident involving multiple vehicles the police may investigate whether the driver of any of the vehicles is under the influence of or intoxicated by alcohol or drugs, and are not limited to investigating and arresting only the driver who was at fault in the accident, for example.
In Washington State, law enforcement officers have the authority to investigate any driver involved in a car crash for driving under the influence (DUI) of alcohol or drugs, regardless of who is at fault for the accident. This means that during the investigation of a multi-vehicle incident, if the police have reasonable grounds to believe that any of the drivers are intoxicated, they can conduct field sobriety tests, request breath or blood tests, and potentially arrest drivers for DUI. Washington's DUI laws, codified in RCW 46.61.502, prohibit operating a motor vehicle while under the influence of intoxicating liquor, marijuana, or any drug. The state's implied consent law, RCW 46.20.308, also stipulates that drivers have consented to a breath or blood test if arrested for suspected DUI. Refusal to take the test can lead to license suspension and other penalties. It's important to note that DUI investigations and arrests can occur independently of the determination of fault in the accident.