Wash. Rev. Code § 26.44.250
A law enforcement officer shall promptly notify child protective services whenever a child is present in a vehicle being driven by his or her parent, guardian, or legal custodian and that person is being arrested for a drug or alcohol-related driving offense. This section does not require law enforcement to take custody of the child unless there is no other responsible person, or an agency having the right to physical custody of the child that can be contacted, or the officer has reasonable grounds to believe the child should be taken into custody pursuant to RCW 13.34.050 or 26.44.050. For purposes of this section, "child" means any person under thirteen years of age.
RCW 26.44.250
Reviser's note: The same language was codified under RCW 46.61.507 pursuant to 2010 c 214 s 1. However, RCW 46.61.507 was further amended by 2012 c 42 s 1 without amendment to this section.