"What's on your mind?" This is a familiar phrase for Facebook users all over the world. However, users of Facebook and other social networking sites are warned of its implications and complications.

Posting on one's wall has been a means of self-expression to many Facebook users, but posting about something negative on her boss allegedly caused American Dawnmarie Souza her job.

In the latest update about Souza's labor case against her former employers, the American Medical Response (AMR), she gets the support of the U.S. National Labor Relations Board (NLRB).

Reports from CNN.com and epoctimes.com said the NLRB, which investigates unfair labor practices, had sided for Souza and has issued a complaint against Conneticut-based AMR.

The company said Souza, a medical technician, was illegally fired because of her negative comments about her supervisor on Facebook.

CNN said in an interview with the NLRB that AMR illegally terminated Souza and denied her access to union representation during an investigatory review.

The Connecticut regional board director Jonathan Kreisberg told CNN that social networking sites like Facebook is generally "a protected concerted activity."

"You are permitted to talk about terms and conditions with employees or anyone else, it's public because you are protected under the National Labor Act," said Kreisberg, the board's regional director in Hartford, Connecticut in the CNN report.

"It was Souza's ... own page; she did this on her own time in her own home. This case is different because in this situation it happened online and the company's rules were unlawfully broad," said Kreisberg.

In a statement to CNN, American Medical Response said it believes that the offensive statements made against the co-worker were not activities protected under federal law.

The company "denies the allegations made by the NLRB and believes the facts will show that they are without merit. The employee in question was discharged based on multiple, serious complaints about her behavior," the AMR statement said.