Weeks into a wave of historic strikes, and days before a planned Black Friday showdown, Walmart has filed a National Labor Relations Board charge alleging that the pickets are illegal and asking for a judge to shut them down. Walmart is no stranger to the NLRB: labor groups have filed numerous charges there accusing the retail giant of punishing or threatening activist workers, including dozens over the past few months. But this charge is the first one filed by the company in a decade. It will pose a decision for a judge and, even sooner, for the Labor Board’s Obama-appointed acting general counsel, who’s been a lightning rod for past Republican attacks.

The National Labor Relations Board, created by the 1935 National Labor Relations Act, is tasked with enforcing and interpreting private sector labor law. Walmart’s charge, filed Thursday night and reported by Reuters Friday evening, sets two processes in motion. The first, which could take months, is the full investigation and resolution of the allegation, beginning with fact-finding by board agents based in Walmart’s backyard (NLRB Region 26, which covers Arkansas and three other states). The second, which could advance as soon as this week, is the decision whether to grant an injunction restricting strikes against Walmart while the investigation proceeds. Experts say NLRB Acting General Counsel Lafe Solomon would have final say over whether the board seeks the injunction; if it does, a district court judge will decide whether to grant it.

Reached over e-mail, Walmart Director of National Media Relations Kory Lundberg said that the company filed the charge in part because “many of our associates have urged us to do something about the UFCW’s latest round of publicity stunts…” In an e-mailed statement, Dallas OUR Walmart member Colby Harris called Walmart’s charge “baseless,” and said, “Walmart is doing everything in its power to attempt to silence our voice.”

While the NLRB is most often criticized by conservatives, its swiftest and strongest remedies are devoted to restricting unions. Federal law requires the NLRB to prioritize employers’ allegations of illegal picketing over other charges, and to request an injunction to stop the picketing if it finds “reasonable cause” to believe such allegations are correct, and expects to issue a complaint (the equivalent of an indictment). So injunctions restricting picketing are often granted within a few days of workers’ going on strike (in contrast, workers who allege they were fired for their union activism often wait for months, injunction-less, to find out whether they’ll get their jobs back). Experts say that, if Walmart has strong enough evidence, an injunction could potentially be issued in time to block Black Friday pickets. But that’s a very big “if.”

Walmart’s charge alleges that the United Food & Commercial Workers (UFCW) union is responsible for illegal “representational” picketing – that is, strikes designed to win union recognition from Walmart. Labor law generally forbids unions from engaging in representational pickets for more than thirty days (the US Supreme Court does not apply the same First Amendment protections to labor picketing as it does to “God Hates Fags” pickets at funerals).

Based on Walmart’s charge, and a cover letter sent to the UFCW, the NLRB faces two main questions. First, has OUR Walmart, the group organizing the Walmart store strikes, been acting as an affiliate or agent of the UFCW? And second, are these in fact representational strikes, as Walmart alleges, rather than strikes protesting “Unfair Labor Practices,” as OUR Walmart claims? On both questions, Walmart says yes; OUR Walmart and the UFCW say no.

On the first question, Marshall Babson, a former NLRB member appointed by President Reagan, predicted that the board would consider factors including whether UFCW was providing OUR Walmart with “monetary support” or “logistical support,” whether there’s been “coordination of efforts,” whether the UFCW has provided “a written set of instructions to picketers, anything like that,” and whether the union offered any “ratification or condonation” of the pickets after the fact. Among other significant ties, The New York Times’s Steven Greenhouse and Stephanie Clifford reported that the UFCW listed OUR Walmart as a “subsidiary organization” on a 2011 filing; the UFCW told the Times that the organization has since “grown and gained independence.”

If Walmart is able to convince the NLRB that OUR Walmart was acting as an agent of UFCW, it would still have to prove that the strikes are illegal. US labor law distinguishes among different kinds of strikes, including “Unfair Labor Practice” strikes, which are motivated by violations of labor law, and “recognitional” strikes, which are designed to pressure a company to recognize a union. ULP strikes have the greatest protection, including a ban on management permanently replacing strikers; recognitional strikes face the greatest restriction, including the thirty-day limit (A secondary issue is how the thirty-day rule applies so far to these strikes, which have been staged at a series of different stores across the country for a day or two at a time).

In statements and media interviews, OUR Walmart members and UFCW officials have consistently named ending retaliation, not winning unionization, as the motivation for their strikes. Asked what evidence Walmart has that the strikes are in fact recognitional, Walmart's Lundberg e-mailed: “The letter to the UFCW spells out the legal aspects of the ongoing ‘recognitional picketing’ that has clearly been happening for more than 30 days and is against the law.” But that letter does not offer any examples of evidence that the workers are engaged in a recognitional strike.

Wilma Liebman, a former Obama-appointed NLRB Chair, said that the NLRB could consider factors including language on signs or leaflets, statements by picketers, communications between organizers and management and internal union memos. Even if some workers are on record saying that they want to unionize, said Liebman, that wouldn’t be enough to show that winning union recognition was the purpose of the strikes.

To prove that the strike is recognitional, said Babson, “There really has to be a demand for recognition from the employer. It’s that simple.” According to Babson, who’s now a management-side labor law attorney for the firm Seyfarth Shaw, “The way many employers deal with this, and this is something you learn in management labor lawyer school 101, is you send somebody out there to the picket line,” ask who’s in charge, and “you say, ‘What do we have to do to get you to go away?’ If they say recognize the union, then that’s it, that’s the end of the inquiry.” But “If they said, ‘We want you to treat us better, we want you to pay wages and benefits that are more comparable with the area standards,’ that’s not recognitional picketing, unless there’s some other evidence.”

Babson also noted that if workers are “vindicated” at the NLRB in their allegations of Unfair Labor Practices, “then that would undercut the basis for arguing that any of that activity” was recognitional.

So will a court shut down the pickets? Babson said simply that Walmart had made “very important and significant allegations, and like everything else, they’ll turn on the quantum and quality of evidence that will be presented.” Others experts were more dubious about Walmart’s chances. “I would be very, very surprised if the board finds any substance” to Walmart’s charge, said John Logan, the director of labor and employment studies for San Francisco State University.

“Do I believe that the UFCW is organizing these actions? Yes,” said Kate Bronfenbrenner, Cornell’s director of labor education and research. “But are they in violation of the National Labor Relations Act? No. As written, these are not recognitional strikes…. the UFCW is not doing anything illegal.”

Bronfenbrenner called Acting General Counsel Solomon “a very independent person,” and predicted that he would reject Walmart’s allegation of illegal recognitional strikes. If that happens, she said, Republicans may launch an attack on the NLRB similar to the one they mounted over its investigation of the politically connected aerospace giant Boeing last year.

Liebman said based on the publicly available information, “I don’t think the threshold is met” for Walmart to get its injunction. But she said that may not be Walmart’s real goal: “My guess is that what Walmart is fearful of is that this [strike] is going to work on Friday, and it’s really going to disrupt operations. So they’re trying to chill that.”

Walmart’s letter to the UFCW accuses the union of “enlisting [workers] in orchestrated schemes to disrupt Walmart’s business operations by telling them that federal labor law protects their participation” in strikes that are in fact illegal, and thus could get them fired (the letter also alleges that the protests involve a range of crimes beyond those in the NLRB charge, including trespassing). A Walmart spokesperson drove a similar message home Sunday, telling CNN that if workers don’t show up on Black Friday, “there could be consequences.” The target audience for that statement, and for Walmart’s latest legal salvo, may not be the media, or the courts, or the UFCW, but the thousands of workers who want to see change at Walmart but have haven’t yet decided whether going on strike is worth the risk.

UPDATE: Walmart has sent store managers a message to employees saying they could "get disciplined" for striking. Josh Eidelson reports.