The term “whistleblower” has become widely used in recent years. But as a legal matter, what is a whistleblower? Well, that depends on the law being applied. Various statutes contain protections for whistleblowers, and those statutes usually have a detailed definition of who qualifies as a whistleblower under that particular law. Likewise, each statute generally describes the rights and remedies of someone who qualifies as a whistleblower.
Focusing on employment law, the federal anti-discriminatory statutes (e.g. EEOC, ADA, FMLA, ADEA) each protect whistleblowers. In Pennsylvania, there is a whistleblower law, but it only applies to employers in the public domain, not to purely private employers. Famously, NJ has the Conscientious Employee Protection Act, which provides broad protection for whistleblowers.
As per normal, there a various twists and turns in working through the details of the law. But as a general matter, a whistleblower is someone who opposes an unlawful employment practice by refusing to participate in it, or by reporting it to the appropriate authorities, or by participating in an investigation as a witness or source of information. Retaliation against a whistleblower is unlawful. Retaliation can take many forms, including any tangible adverse action against the whistleblower (i.e. termination, suspension, demotion). In order to prevail on a claim, the whistleblower must establish a causal connection between the whistleblowing activity and the alleged retaliation. That causal link may be established by showing a proximity in time between the whistleblowing and the retaliation.