What will happen to the workers who participated? Business owners who supported their striking employees geared up in advance, preparing to run limited services, letting customers know about the disruption, and clarifying the company’s policy for “A Day Without Immigrants” with their employees. For other businesses, however, there seemed to be some confusion regarding how to handle the situation.

For workers without such amenable employers, the issue is thornier. Before the strike, law firms specializing in employment law and human resources advisers published articles warning employers to refrain from disciplining workers participating in “A Day Without Immigrants,” and instead suggested talking to their employees and working out an arrangement allowing them to participate. A notice sent by the Colorado Restaurant Association advised its members not to take action against employees participating in the strike, beyond not paying those who decided not to show up.

The legality of the firings remains a gray area, and likely comes down to the National Labor Relations Board (NLRB). “The answer is somewhat murky,” says Charlotte Garden, an associate professor at the Seattle University School of Law and an expert in labor law, over email. “The National Labor Relations Act protects workers’ rights to engage in concerted activity for mutual aid or protection, and the scope of what falls under that umbrella is quite broad. So it is likely that some forms of worker protest about the likely effects of Trump Administration policies on immigrant workers would be protected. But that protection would not necessarily include every tactic that workers might use.” Garden explained that while it’s clear that employers can’t fire workers for talking about striking, it’s unclear whether missing work for the strike would be protected by the NLRA.

While 2017’s protest took on a special urgency, it is not the first year one like it has been held. After the 2006 “Day Without Immigrants,” the NLRB sided with employers, saying they did not violate the NLRA for firing workers who missed work to attend the protest, since protesting the federal government’s immigration policies is not employer-related. Two years later, however, the NLRB clarified its guidelines for political advocacy. Under the new directions, while striking for “mutual aid or protection” is legally protected, those protesting immigration policies can be disciplined “neutrally.” How the National Labor Relations Board’s General Counsel interprets those guidelines now, will determine whether or not workers have recourse. Richard Griffin, who was nominated by Obama in 2013 and whose term runs through the end of this year, currently holds the position.

Even if the law would ultimately vindicate the strikers’ case for immunity from being fired for participating in the protest, the legal battle is an uphill one, and suing may not be the easiest route. As Garden explained, the process of winning reinstatement and back pay from the NLRB is a long and cumbersome one. Haeyoung Yoon, the director of strategic partnerships and an expert on workplace-standards at the National Employment Law Project, added that while some of the fired workers may potentially be able to file a retaliation claim, the merit of those cases depends on the specific circumstances on a case-by-case basis. For workers who are looking for a more immediate and dramatic course of action, speaking out about their job loss—and thus becoming a PR nightmare for their former employer—is a better bet, though it ultimately won’t provide a new job or make up for lost wages.