A federal proposal to have information about joining unions added to the collection of mandated posters hanging in your company breakroom was rejected by the DC Circuit Court on Tuesday. The Court's argument, in short: The government can't threaten to punish a business for deciding to keep its mouth shut.

Workers at nearly all American businesses have the right to join a union. They exercise that right far less frequently than they used to — union density is at a 97-year low. This is in some small part, the labor movement thinks, because they don't know about it. SO labor successfully pushed the National Labor Relations Board to mandate that employers display a list of workers' collective bargaining rights, a rule that was supposed to go into effect in January.

Businessweek describes what the NLRB mandated.

The poster rule would have required more than 6 million businesses to display an 11-by-17-inch notice in a prominent location explaining the rights of workers to join a union and bargain collectively to improve wages and working conditions. The posters also made clear that workers have a right not to join a union or be coerced by union officials.

The NLRB website offers a FAQ on the topic which outlines the punishment mechanism. While the NLRB "does it have the ability to assess fines or penalties," it explains:

A failure to post the Notice would need to be brought to the Board’s attention in the form of an unfair labor practice charge by employees, unions, or other persons.

In the complex jargon of labor law, an "unfair labor practice charge" is a claim filed arguing that one side or the other in a labor dispute has violated the National Labor Relations Act. It's sort of like if everyone in a soccer match had a yellow card that they could pull when they saw a foul, then allowing the referees — here, the NLRB — to investigate. If a violation of the law is found, the NLRB can take action. In practice, this is a slow, tedious process.

But the DC Circuit Court thought that, in this case, it was also hypocritical. The Court got the case after the National Association of Manufacturerrs and another business advocacy group sued to block the NLRB's rule. Law360.com describes the Court's decision:

[The Court] found that the rule could not survive because of Section 8(c), which states that the expression or dissemination of views cannot constitute an unfair labor practice as long as the expression contains no threat of reprisal or promise of benefit. …

"Suppose that Section 8(c) prevents the board from charging an employer with an unfair labor practice for posting a notice advising employees of their right not to join a union. Of course Section 8(c) clearly does this," the appeals court's opinion said. "How then can it be an unfair labor practice for an employer to refuse to post a government notice informing employees of their right to unionize (or to refuse to)?"

In other words, unions aren't allowed to pull their yellow cards if a business posts non-threatening information about the right to not join a union. Why should the opposite be the case? That distinction, the Court decided, violated the businesses' right to free speech.

Understandably, the labor movement isn't happy about the decision. In a phone interview with The Atlantic Wire, Peter Ford, an attorney with the United Food and Commercial Workers, a union that primarily represents employees at grocery stores, said the union, which primarily represents employees at grocery stores, is "certainly disappointed." While Ford hadn't yet read the decision, he indicated that it was certainly possible that the decision could lead to more challenges to the mandatory postings in workplaces.

It seems unlikely that the NLRB posters would have made much of a dent in waning levels of union density, though the notices also reinforce other, less formal collective rights. After all, most workers pass by those other posters every day, including one that articulates the federal minimum wage in large type. If you asked, how many do you suspect could tell you that figure?