RCW 69.50.408: Second or subsequent offenses.

(1) Any person convicted of a second or subsequent offense under this chapter may be imprisoned for a term up to twice the term otherwise authorized, fined an amount up to twice that otherwise authorized, or both.

(2) For purposes of this section, an offense is considered a second or subsequent offense, if, prior to his or her conviction of the offense, the offender has at any time been convicted under this chapter or under any statute of the United States or of any state relating to narcotic drugs, cannabis, depressant, stimulant, or hallucinogenic drugs.

(3) This section does not apply to offenses under RCW 69.50.4013.