When is a poster not considered an innocent proclamation of pre-teen musical tastes? When it involves a governmental agency overstepping its bounds and requiring employers to post mandatory notices advertising the National Labor Relations Board’s (NLRB) ideological views about unionization.

A South Carolina district court has begun hearing arguments in a lawsuit against the NLRB challenging the Board’s new rule requiring businesses to post notices explaining employees’ rights to unionize.

The lawsuit, brought by the South Carolina Chamber of Commerce and the U.S. Chamber of Commerce, alleges that the misguided NLRB rule violates federal labor and regulatory laws as well as First Amendment free speech rights.

THe lawsuit notes that the NLRB did not analyze the impact of the proposed rule on small businesses, as it is required by law to do. The suit also asserts that the NLRB lacks the statutory authority to impose the notice requirement, and that the rule violates the First Amendment by compelling employers to post the NLRB’s ideological views on unionizing. Finally, the rule is arbitrary and capricious, according to the lawsuit because it does not include a description of the fundamental rights of employees to be free of compulsory union membership and dues or the consequences of unionization.

In a press release issued when the lawsuit was filed, Robin Conrad, executive vice president of the National Chamber Litigation Center, stated “the NLRB has no authority to impose any of these requirements. This is nothing more than labor regulation run amok. Adding insult to injury, the Board’s new rule violates the First Amendment by forcing employers to use their own resources to post the NLRB's pro-union message on the company’s own property.”

The NLRB rule—adopted by the board in August— was originally slated to take effect on November 14, 2011. However, faced with multiple court challenges as well as congressional efforts to overturn it, the NLRB postponed the rule’s effective date to January 31, 2012. The posting deadline has now been extended to April 30, 2012.

The case, Chamber of Commerce, et al. v. National Labor Relations Board, et al. is in the U.S. District Court of South Carolina.