Protesting workers may need to be extra cautious about whose hand they’re trying to force in the wake of a recent NLRB ruling that will likely affect labor advocacy in a number of industries.

The National Labor Relations Board recently ruled that a group of subcontracted janitors were justifiably fired for picketing at the San Francisco building where they worked. The board said the workers weren’t protected by federal labor law because they were trying to convince the building’s property manager to cut ties with their employer.

Workers and their unions can picket or protest at job sites with multiple employers. They can also inform a “secondary” or “neutral” employer that they plan to do picketing directed at the primary employer they work for. But it’s generally unlawful to coerce a secondary employer to stop working with the primary business they have the dispute with.

The janitors in this case were employed by Ortiz Janitorial Services, which was subcontracted by Preferred Building Services to provide cleaning services in a building managed by Harvest Properties. During their protests, the workers noted that Preferred was their employer, and called on one of the building’s tenants to act. They also had a meeting with Harvest where they asked for changes to be made. The board said those moves showed that they had the unlawful objective of getting a neutral to terminate its contracts with their own employer.

The decision suggests the Republican-controlled NLRB will likely be looking closer at workers’ picketing and protests on job sites where multiple businesses operate. Some worker advocates told Bloomberg Law the ruling also signals that the board is likelier to find that those sorts of actions by workers are “secondary” activities not protected by law.

The ruling takes on added significance as unions are pushing their agendas heavily before the midterm elections, and worker actions targeted at multiple employers and industries are spreading across the country. It also comes as the board’s general counsel has made other moves that could limit worker protest actions and make it easier for employers to lawfully punish those who participate.

A New Line on Unlawful Picketing?

The Ortiz janitors and their backers—the San Francisco Living Wage Coalition and a local affiliate of the SEIU—called for higher wages and said they wanted something done about an OJS supervisor’s alleged sexual harassment.

But the board said the workers’ actual goal was to pressure Harvest to stop doing business with OJS unless the company addressed those issues.

Management- and union-side attorneys who spoke with Bloomberg Law disagreed on whether the board has drawn a new line separating lawful picketing from unlawful “secondary picketing.”

Federal labor law “prohibits picketing where ‘an object’ is to pressure a neutral to cease doing business with the primary employer,” Zachary Fasman, a partner at Proskauer Rose who represents employers in collective bargaining and litigation involving union and employee relations, told Bloomberg Law. “It’s hard to fault the board for reaching the conclusion that ‘an object’ here was secondary in nature.”

Worker advocates and one former NLRB chairman said the decision appears to be a subtle but remarkable change to a long-standing approach the board has taken in these sorts of cases.