In its latest legal defeat, the National Labor Relations Board was slapped down Wednesday by the District of Columbia Circuit Court of Appeals in a bid to revive its so-called "poster" ruling. A similar appeal by the NLRB to the Fourth Circuit Court was also struck down Aug. 12.

The rule, which the NLRB adopted in 2011, would have required all businesses to prominently place posters in the workplace explaining workers' rights to join a union.

Failure to do so would itself be evidence of a hostile work environment towards union activities, the NLRB said. Those posters would not include other information though, such as how to de-certify a union or how workers can opt out of paying dues.

Employers have pushed back and won a several court battles. The DC Circuit Court vacated the NLRB's ruling in May, saying it violated the First Amendment. In June, the Fourth Circuit Court of Appeals also ruled against the board, saying it exceeded its authority under the National Labor Relations Act.

In a statement Wednesday, National Association of Manufacturers President Jay Timmons claimed the poster rule is "a prime example of the aggressive agenda pursued by the NLRB in recent years, and the court has correctly decided that that the board has overstepped its authority."

A spokesman for the NLRB declined to comment to the Washington Examiner.