The National Labor Relations Board regulates workplace policies and conduct under the National Labor Relations Act (NLRA). This statute sets policies for most private employers and employees and tries to balances the rights and freedoms of employees with the needs of employers to maintain a certain code of respect and order. Recently, the proliferation of social media sites and employees using such sites on a regular basis, including during the work day, has provided a vast new area of law that the NLRB must re-evaluate. Employees who post complaints on sites such as Facebook can be lawfully terminated, provided the comment is intended to vent or just complain. If, however, an employee posts a comment that is a "concerted activity," meaning that it involves other employees, and is meant for the purpose of initiating or promoting group action to bring to the attention of management serious issues that need to be addressed, it is protected activity. Such protected activity cannot be the basis for termination of an employee as the NLRA is meant to allow employees to discuss legitimate grievances so that management can attempt to fix the problems and provide a better environment for its employees. But the line between "protected activity" and "mere venting" can be blurry at times, leading to lawful termination of an employee who thought he was following the guidelines for protected speech. It's best to be safe rather than sorry and a heated comment on social media made when you are frustrated could mean you lose your job. So rather than risk it, keep your frustrations out of the workplace and offline!
See Raphael Rajendra, Employee-Owned Devices, Social Media, and the NLRA, 30 ABA Journal of Labor and Employment Law 47 (2014).