HARTFORD, Conn.—The outcome of a lawsuit filed on behalf of a union-represented employee who was fired for criticizing her supervisor on Facebook could affect employers nationwide, including those with nonunion workforces, experts say.

In what some labor law attorneys call a “shot across the bow,” a regional office of the National Labor Relations Board sued medical transportation firm American Medical Response of Connecticut Inc., alleging it illegally terminated and illegally denied union representation to the employee during an investigatory interview.

The suit also alleges that the company maintained and enforced an “overly broad” blogging and Internet posting policy.

The complaint, which the NLRB brought in late October, challenges not only the grounds on which the employee was fired but also is an effort to clarify that employer social media policies should not be designed to prohibit employees from using social media and do not infringe on protected “concerted” activity under the National Labor Relations Act.

Dawnmarie Souza, a union worker for AMR's New Haven office, was fired in December 2009 after disagreements between her and her supervisor. The friction that lasted about a month culminated when Ms. Souza was asked by her supervisor, Frank Filardo, to prepare an incident report and take part in an interview about a client's complaint about Ms. Souza's work, according to the NLRB complaint.

Ms. Souza asked that a Teamsters Local 443 representative be present during the interview, which management denied and threatened disciplinary action because of her request, according to the complaint.

Later that day, Ms. Souza went on her personal Facebook page at her home computer and posted a negative remark about her supervisor, which drew supportive responses from her co-workers and more negative comments by Ms. Souza, according the NLRB investigation. It was reported that Ms. Souza questioned “how the company allows a 17 to be a supervisor” in her posts. The reference to 17 is AMR's jargon for a psychiatric patient, according to reports.

The NLRA safeguards the rights of employees to organize into a union, said Irving M. Geslewitz, a principal and labor and employment attorney at Much Shelist Denenberg Ament & Rubenstein P.C. in Chicago, but it also protects employees who want to band together for mutual aid or protection even if they are not in a union.

“In this case, there was a union in the picture, but that was just incidental,” Mr. Geslewitz said. “This employee was talking with other employees (using social media) about a supervisor that she thought was being unfair and other employees chimed in. A lot of people don't know that the NLRA protects that type of "concerted mutual aid or protection' activity even if it does not involve a union.”

Greenwood Village, Colo.-based AMR terminated Ms. Souza, saying she had violated the company's Internet policies with her postings. The NLRB's Hartford, Conn., regional office, however, argues in the suit that her Facebook postings were a “protected and concerted activity” and that AMR's blogging and Internet posting policy contained “unlawful provisions, including one that prohibited employees from making disparaging remarks when discussing the company” and another that “prohibited employees from depicting the company in any way over the Internet without company permission.”

In a statement, the NLRB said such provisions interfere with employees' right to engage in concerted activity.

The fact that it occurred on Facebook and not in the office break room doesn't change the rights employees have when discussing the terms and conditions of their employment, said Seth Borden, New York-based partner in McKenna Long & Aldridge L.L.P.'s labor practice.

“It doesn't matter where the employees are talking together about their terms and conditions of employment,” Mr. Borden said. “They have that right under the NLRA. Whether it's done in the break room or on Facebook, the right doesn't change, only the medium has.”

Mr. Borden said the NLRB's decision to file a complaint “is the clearest example by the board that they intend to make sure the law is responsive to new technology” and that “this is just a shot across the bow” for employers.

In a statement, AMR rejected the NLRB's assertions and said it believes “the facts will show that they are without merit” and that Ms. Souza “was discharged based on multiple, serious complaints about her behavior.”

Further, AMR said Ms. Souza was being held accountable for negative personal attacks on Facebook, and that “the offensive statements made against (Mr. Filardo) were not a concerted activity protected under federal law.”

What's not clear in the NLRB's complaint is how AMR gained access to Ms. Souza's Facebook postings.

If the supervisor had access to Ms. Souza's profile, it would be assumed that he had access to her posts and that would not constitute unlawful surveillance, Mr. Borden said. Unlawful surveillance of someone's profile activity on social media sites could occur if a supervisor presses other employees to “friend” or “follow” a co-worker to report their activities.

Labor and employment law attorneys said employers should have a social media policy that complies with the NLRA. Employers also should have a uniform way of monitoring social media networks, said Eric B. Meyer, Philadelphia-based employment law attorney and associate with Dilworth Paxon L.L.P., as to not void their social media policy.

“Employers who have a social media policy reserve the right to monitor social media activity of all employees, but this doesn't mean that they do so,” Mr. Meyer said. “If employers choose to monitor social media activity of their employees, they should be uniform across the board. They should not just monitor certain individuals unless they have reason to do so, such as disseminating proprietary information or unlawful harassment of other employees.”

But had Ms. Souza's comments about her boss gone too far? Mr. Geslewitz said that while most speech by employees is protected, even in social media forums there are times when they can go too far.

“She was really bad-mouthing (her supervisor) and the other employees were jumping in and adding disparaging comments in a public forum,” he said. “It will be a contested issue as to whether she may have gone too far and, therefore, it was unprotected (by the NLRA).”

The case will go before an NLRB administrative judge and a hearing is set for Jan. 25, 2011.

According to an NLRB spokeswoman, if the case is appealed and reaches the board level of the Washington-based federal agency, that decision will set a precedent for all companies' blogging and Internet posting policies nationwide.

“I'm not surprised by the attention this case is getting,” said Philip L. Gordon, Denver-based shareholder and labor law attorney for Littler Mendelson P.C. “I think employers have been putting in social media policies over the years, but there isn't a lot of guidance on how they should be interpreted or how they should be put together.”