Whistleblower is a term applied to a person who reveals misconduct within an organization, to the public or to those in positions of authority. The whistleblower is a person, usually an employee, in a government agency or private enterprise who makes a disclosure to the public or to those in power, of mismanagement, dishonesty, illegality, or some other wrongdoing.

Since the 1960s, the public value of whistleblower has been increasingly recognized. Federal and state statutes and regulations have been enacted to protect whistleblowers from various forms of retribution. Even without a statute, a number of decisions encourage and protect whistleblowers on grounds of public policy. The federal False Claims Act (31 U.S.C.A. 3729) also rewards a whistleblower that brings a lawsuit against a company, which makes a forged claim or commits fraud against the government.

People performing the role of whistleblowers are often the subject matter of retaliation by their employers. Normally the employer discharges the whistleblower, who is often an at-will employee. At-will employees are people without a specific term of employment. The employee may quit at any time and the employer has the right to fire the employee without having to quote a reason. However, the judiciary and legislatures have formed exceptions for whistleblowers that are at-will employees. Employees who blow the whistle on issues that affect only private interests will generally be unsuccessful in maintaining a cause of action for expulsion in violation of public policy. As a general rule, employees asserting that they were dismissed for disclosing internal corporate misconducts have been unsuccessful in determining public policy exceptions to the at-will rule. It is also seen that grievances about internal company policy do not involve public policy supporting unjust dismissal suits.

Many states have enforced whistleblower statutes to protect and safeguard the interests of the whistleblower, but these statutes vary widely in coverage. Some statutes tend to apply only to public employees, some apply to both public and private employees, and others apply to public employees and employees of public contractors.