RCW 49.99.070: Collective bargaining units—Determination, modification, and combination.

The commission, after hearing upon reasonable notice, shall decide in each application for certification as an exclusive bargaining representative or unit clarification, other than applications submitted under RCW 49.99.050, the unit appropriate for the purpose of collective bargaining. In determining, modifying, or combining the bargaining unit, the commission shall consider the duties, skills, and working conditions of the employees; the history of collective bargaining by the employer and their bargaining representatives; the extent of organization among the employees; and the desire of the employees, and the avoidance of excessive fragmentation.