It is illegal for an employer to punish you for doing the right thing. We protect employees who spoke up — and paid for it.
An employer may not retaliate against you for opposing unlawful discrimination — based on any protected category such as age, disability, gender, national origin, pregnancy, race or religion — or for filing a charge of discrimination with the EEOC or an equivalent state agency, testifying, or participating in any way in an investigation, proceeding or lawsuit under federal or state discrimination laws.
Federal law also protects employees of publicly-traded companies who report certain types of fraud. "Qui Tam" or "False Claims" cases allow employees who learn their employer is defrauding the federal government to report it — and potentially recover a portion of the proceeds the government recovers.
Many specific whistleblower and retaliation statutes protect everyone from nurses to executives to over-the-road truck drivers and airline pilots. An experienced employment lawyer can help you determine which protections apply to your situation.