Federal regulators say union activists have the legal right to display giant inflatable rats outside companies during labor disputes.

The National Labor Relations Board says putting up a 16-foot-tall rat balloon is allowed even if the business is not directly involved in the conflict between the union and another employer.

The Carpenters union and other labor groups often use the giant rat as a form of street theater. The goal is to shame companies that hire outside contractors who refuse to use union workers or pay union-scale wages.

The case was closely watched by business groups who claim the giant rat is too coercive and confrontational. But the labor board says the rats are a form of symbolic speech that don’t interfere with business activity.