The National Labor Relations Board decided this week that employers and staffing agencies no longer have to consent before a union can combine solely and jointly employed workers into one unit. The NLRB’s decision overrules a 2004 decision from the Board.

The 3-1 decision in Miller & Anderson, Inc. and Tradesmen International and Sheet Metal Workers International Association, Local Union No. 19, AFL–CIO held that a union does not need consent from user and supplier employers in order to create a unit that combines employees of the user employer with employees who work for the user and supplier.

Practically speaking, this means that employers who use temporary employees from staffing agencies could see their temp employees combined into a union with permanent employees without the employer’s consent. The permanent and temporary employees must still share a “community of interest” in order for the Board to consider a single unit to be appropriate.

The majority of the NLRB in the Miller & Anderson decision reiterated the Board’s view that the primary purpose behind the National Labor Relations Act was to encourage and facilitate collective bargaining, and that “self-organization” includes the right to determine who is included and who excluded from any bargaining unit.

“Limiting the contingent employees to [a separate union or seeking employer consent] deprives them of the full ability to associate for collective bargaining purposes with their coworkers who are solely employed by the user employer,” the majority wrote. “It also deprives the solely employed employees of their full ability to associate with their contingent coworkers . . . It dilutes the bargaining power of both groups.”

The Miller & Anderson decision represents a complete 180 from the Board’s 2004 holding in Oakwood Care Center, which held that solely and jointly employed workers need consent from both employers in order to join the same bargaining unit.

“Oakwood denies employees in an otherwise appropriate unit full freedom of association,” the Board found this week. “Requiring employees to obtain employer permission to organize is surely not what Congress envisioned when it instructed the Board . . . ‘to ensure to employees the fullest freedom in exercising the rights guaranteed by the [NLRA].’”

The decision overturned a regional director’s ruling that the union could not represent construction workers employed by both Miller & Anderson Inc., an electrical and mechanical contractor, and Tradesmen International. Employer groups filed briefs asking the Board to stick to Oakwood, but national unions argued in favor of rejecting Oakwood.

This week’s decision follows the Board’s trend in recent years of chipping away at pro-employer precedents, particularly in the area of joint employees. Employers who contract with staffing agencies or otherwise use temporary employees should make sure they’re prepared for potential joint unionization activities.