Contractors Labor Pool is a major supplier of construction trade labor to nonunion contractors in the western United States. CPL implemented a new hiring guideline, based on a company retention study, under which it refused to hire applicants whose most recent job was at a pay level that was more than 30% above starting wages paid at CLP assignments. The guideline effectively excluded most electrician applicants who had recently worked on a construction project that paid union wages. Some union salts who were denied employment under the rule filed an unfair labor practice charge with the National Labor Relations Board. The NLRB held that even if the CPL hiring guideline was not motivated by union animus, it was an unfair labor practice because it was inherently destructive of employees’ right to organize.