American Medical Response (NLRB). Illegal to terminate employee for comments regarding supervisor because employer's social media policy was too broad in that it prohibited concerted activity (allowing employee to discuss wages, hours, and working conditions).
Electronic Communications Privacy Act (ECPA) and Stored Communications Act (SCA). Prohibit unlawful access to stored electronic communications (Exceptions exist where voluntary consent (implied or direct) is obtained to gain access on company computers. Note: Some states (e.g., Illinois, Delaware) have more stringent laws. Key: Did employee have reasonable expectation of privacy? Thygeson v. U.S. Bancorp (D. Ore. 2004) (court held no reasonable expectation of privacy by employee who was fired for excessive use of internet/lewd comments because employee used company network to access content); Pietrylo v. Hillstone Rest. Group (D.N.J. 2009) (violation of SCA because employer pressured co-worker to obtain MySpace password).
Legal off-duty laws. In some states (e.g., California), can't fire employee for intoxicated Facebook pictures if employee is of legal drinking age.
Whistleblower laws. State laws/SOX. Is social media comment related to poor working conditions, safety, or fraud violations?
Child pornography laws. Some states (e.g., Illinois, Michigan, Missouri, etc.) have mandatory reporting statutes that require IT to report child pornography found on computers they service.
FTC reporting requirements. Employers may face liability when employees comment on company products or services on social media without disclosing employment relationship.