Complaining about your employer on social media can't get you fired if it is intended for the "mutual aid" of co-workers, CNNMoney.com reported.

The National Labor Relations Board (NLRB) said today that the National Labor Relations Act, passed in 1935, applies to people venting on Facebook. The act was originally passed to protect workers' rights to organize a union. 

The NLRB's decision in the recent case, Hispanics United of Buffalo, Inc., was one of the first decisions to address the issue of social media as it relates to employee rights. 

In that case, one employee, Lydia Cruz-Moore, criticized another, Marianna Cole-Rivera, and threatened to take her complaints to the nonprofit's executive director. Cole-Rivera responded with a Facebook post saying "Lydia Cruz, a co-worker, feels that we don't help our clients enough at (Hispanics United). I about had it! My fellow co-workers, how do you feel?"

Four other employees responded, and all five were fired a couple of days later.

The NLRB's ruling against Hispanics United goes a little way toward answering the question of what is acceptable for employees of a company to discuss about the company on social media. Similar hypothetical situations were posed in a Business Record article last year. Responses showed that answers to HR-related social media questions are still relatively unknown.