As National Football League team owners consider President Trump's call to fire players who refuse to stand for the national anthem, they have stumbled into one of the most consequential debates in today's workplace: How far can workers go in banding together to address problems related to their employment?
In principle, the answer in the N.F.L. and elsewhere may be: Quite far.
To the extent that most people think about the reach of federal labor law, they probably imagine a union context — like organizing workers, or bargaining as a group across the table from management.
As it happens, the law is much more expansive, protecting any "concerted activities" that employees engage in to support one another in the workplace, whether or not a union is involved. The National Labor Relations Board and the courts have defined such activity to include everything from airing complaints about one's boss through social media to publicly supporting political causes that have some bearing on one's work life.
The league's operations manual says players must be on the sidelines during the anthem and should stand. While the law might not bear on whether an individual player can kneel during the anthem, many experts say it could protect players from repercussions for making such a gesture together — or taking other action — to show solidarity on the job.
And as unionization continues its decades-long decline, some believe that these alternative forms of taking collective action may be crucial to enabling workers to speak up.
"Workers without a traditional organization that is meant to protect them at work are kind of scrambling around for new ways of protecting themselves," said Benjamin Sachs, a labor law professor at Harvard University. "It does feel like these are nascent forms of something new."
To be protected under federal labor law, an employee's action must be conducted in concert with co-workers, it must address an issue of relevance to their job, and it must be carried out using appropriate means. Workers can't, say, damage property or threaten violence. (If the workers have a collective bargaining agreement with their employer that forbids certain actions — like striking — they can't do that, either.)
Many experts believe that some of the recent protests by N.F.L. players meet all three conditions, and that as a result, their teams cannot discipline or fire them for taking part.
These experts point to a 1978 case in which the Supreme Court ruled that workers have a right to engage in political advocacy as long as the political theme relates to their job. In 2008, the general counsel of the National Labor Relations Board, which enforces federal labor law, issued a guidance making clear that workers had a right to publicly demonstrate for or against immigration legislation pending in Congress, though they didn't have the right to skip work to do so.
More recently, the Obama-era labor board appeared to bless a relatively informal definition of the term "concerted activities," so that spontaneous banter, and not just well-orchestrated action like a formal protest, could qualify as protected.
For example, the board ruled that two employees of a sports bar had been improperly fired after one complained on Facebook that their boss had mishandled their tax withholdings and another "liked" a former employee's Facebook complaint. In another case, the board ruled that an employer couldn't fire five workers who had gone on Facebook to object to criticism of their work by a sixth employee.
Together, said Matthew Bodie, a law professor at St. Louis University who is a former attorney for the labor board, these precedents suggest that federal labor law would most likely protect collective protests of the president's argument that players should be fired over political gestures — or his suggestion that league rules designed to protect players from debilitating injury are too strict.
Mr. Bodie added that a player was also likely to enjoy federal protection for any protest in support of other players who had been disciplined.
"If they're standing up for other players' rights to kneel in the context of their job and keep their job, it seems to me to be protected concerted activity," Mr. Bodie said.
Michael J. Lotito, a lawyer with the management-side firm Littler Mendelson, agreed that players who protested Mr. Trump's efforts to stifle their colleagues' political gestures could be engaging in protected activity. But he argued that under the law, which he said the Obama-era labor board had interpreted too broadly, the activity would have to entail more than kneeling during the national anthem.
He said players would need a more overt connection to their cause, like passing out, to other players, fliers that took issue with the president's meddling in their workplace.
Mr. Lotito also said the players' collective bargaining agreement with the owners could lawfully prohibit these sorts of protests. But Michael LeRoy, who teaches sports law at the University of Illinois, said the league's bargaining agreement was somewhat ambiguous on the question of protests with a political dimension.
The N.F.L. and its players association did not respond to requests for comment.
Experts said the "concerted activity" right could be even more profound in workplaces, unlike the N.F.L., where employees aren't unionized and, therefore, have fewer tools for challenging their employers.
"People naturally have complaints, and they don't go away just because you kill unions," said Wilma B. Liebman, a former chairwoman of the labor board during the Obama administration.
Mr. Sachs of Harvard pointed to a case involving a group of employees for a Washington State construction contractor, some of whom produced and publicly released a YouTube video complaining that they were being forced to handle contaminated soil without proper training. The labor board issued a complaint against the company for firing the workers, and the company ultimately settled.
Even James Damore, the Google engineer recently fired for internally sharing a memo about the company's diversity policies that many found offensive, could credibly claim that federal labor law protected his actions, according to Mr. Bodie. To do so, Mr. Damore would have to demonstrate that he had been seeking to enlist his co-workers in questioning the policies, as he has since suggested was his goal.
The Trump administration appears to take a dim view of workers' rights to band together outside traditional union activities. Beyond the president's forays into the N.F.L. controversy, his administration took the unusual stepof reversing the government's position in a worker-rights case pending before the Supreme Court.
The court, which heard the argument in the case last week, must decide how strong a right workers have to band together to sue employers over workplace concerns, like wage theft or safety lapses, or initiate collective arbitration proceedings to address these issues. Courts have generally acknowledged that federal labor law protects workers' rights to bring class-action cases, but there is debate about whether employers can require workers to waive that right through their employment contracts. The Trump administration argues that they can do so.
With a conservative majority on the Supreme Court and a Republican majority on the labor board, federal law is likely to move in this direction.
Even so, there is probably no reversing the trend of employees' piping up en masse in the workplace. "People's instinct, whether you know the word 'solidarity' or not, is to look for people to join you," said Ms. Liebman, the former board chairman. "The growth of social media, Twitter, different avenues for expressing solidarity, is kind of remarkable."