It is always illegal for an employer to retaliate against an employee for any reason. There are federal laws that protect employees from retaliation if they file a complaint against their employer. For example, the Fair Labor Standards Act (FLSA), passed in 1938, provides workers with the right to receive overtime, and if they report their employers for not paying them, they can report it to the US or state labor department without fear of retaliation. If an employee reports an employer for discrimination, it is illegal for the employer to discriminate against the employee. There are laws in place that protect whistleblowers, which are workers from within a company or organization that reports misconduct, immoral, or illegal behavior to the authorities. One of those laws is the Sarbanes-Oxley Act of 2002, enacted in response to major accounting and corporate scandals that occurred in the early 2000s. The Sarbanes-Oxley Act protects employees of publically-traded companies for reporting fraud against shareholders.