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The National Labor Relations Board added a little more clarity to the debate surrounding social media after two recent rulings calling one corporation's policy "overly broad" but also stating that social media postings are not protected under federal labor law.

In recent weeks, the NLRB, an independent federal agency that protects employee rights, ruled that "overly broad" policies are unlawful after the United Food and Commercial Workers Union, Local 371 filed charges against Costco Wholesale Company alleging its social media policy violated the National Labor Relations Act.

The Costco policy stated: "Employees should be aware that statements posted electronically (such as online messageboards or discussion groups) that damage the Company, defame any individual or damage any person's reputation, or violate the policies outlined in the Costco Employee Agreement, may be subject to discipline, up to and including termination of employment."

The NLRB said the overly "broad" policy could be interpreted by employees as an action to prohibit section 7 of the NLRA, which deals with employee rights.

But the NLRB also weighed in on a case involving a car salesman and his series of Facebook postings. An administrative law judge ruled that the firing of a salesman at Knauz BMW was not unlawful because the employee's Facebook updates weren't protected by federal law.

The administrative judge ruled the Chicago-area dealership did not act unlawfully by firing the salesman after he posted a picture of a Land Rover accident, including the caption "Oops." The accident took place after a 13-year-old accidentally hit the gas during a test drive and ran the car into a pond.

"We want to be sure employees know that under federal labor law, they have a right to discuss their wages and working conditions with each other, and to join together to try to improve them. Those rights have existed since the National Labor Relations Act was enacted in 1935, " Nancy Cleeland, director of public affairs at NLRB, told ABC News.

"Today we are merely extending those protections to new forms of communication, such as Facebook. But not all work-related social media posts are protected, and some behaviors can cause an employee to lose protection. We compiled these cases to give both employers and employees a better idea of what is protected and permitted," Cleeland continued.

A post by an employee on a social media website may be protected by the National Labor Relations Act if it relates to working conditions, wages and includes concerted activity. In the case of the BMW salesman, his Facebook postings mocking the luxury dealership for serving hot dogs and bottled water, including the caption "No, that's not champagne or wine, it's 8 oz. water," may have been protected by the NLRA. But the Land Rover picture was not protected speech and that was what got the salesman fired.

As employer restrictions on social media websites become commonplace, the National Labor Relations Board has weighed in on whether social media rules used by employers to govern employees constitute unfair labor practices.

The labor mediation organization released three reports detailing the outcome of numerous cases surrounding social media policies at companies.

In recent months, an Applebee's worker faced firing after he refused to sign an agreement barring employees from making negative comments about the workplace on Facebook. This case has not gone to the NLRB.

"Social media has changed how individuals interact with one another. Its widespread use allows communications to instantaneously reach more people then possibly intended and its online nature may lead to the communications becoming permanent," Adam Forman , a principal in Miller Canfield's Employment and Labor Group, told ABC News.

Forman added, "these factors, combined with the fact that social media is now the norm in our culture, has resulted in line blurring between personal and professional matters. Well-established rules that used to apply in the pre-social media world may no longer make sense."