RCW 9A.04.100: Proof beyond a reasonable doubt.

(1) Every person charged with the commission of a crime is presumed innocent unless proved guilty. No person may be convicted of a crime unless each element of such crime is proved by competent evidence beyond a reasonable doubt.

(2) When a crime has been proven against a person, and there exists a reasonable doubt as to which of two or more degrees he or she is guilty, he or she shall be convicted only of the lowest degree.