Every person who shall wilfully and maliciously, either alone or in combination with others, break a contract of service or employment, knowing or having reasonable cause to believe that the consequence of his or her so doing will be to endanger human life or to cause grievous bodily injury, or to expose valuable property to destruction or serious injury, shall be guilty of a misdemeanor.
RCW 49.44.080
Injunctions in labor disputes: Chapter 49.32 RCW.
Labor unions-Injunctions in labor disputes: RCW 49.36.015.