It is unlawful for an employer to retaliate against an employee for exposing wronging by a superior at work. If your boss takes action against, including issuing "write-ups" or any other disciplinary action for exposing her improper conduct you would have a claim for retaliation. If you were terminated on that basis, you would then have a claim for wrongful termination. You should consult with an attorney to further evaluate the facts and your potential claims.
There are legal protections for employees who make reports about certain categories of wrong-doing, but those categories are very strictly limited to matters of PUBLIC benefit and interest. Most employees who think that they are protected by these laws are NOT, by the applicable (and very narrow) legal definition of the protected categories. By all means, talk with a local employment attorney before you take any action on the assumption (or assurances here based on a few lines of info) that you are protected by law. It can be important to know that an employee is not a "whistle-blower" based on the employee's belief or intention, no mater how well-meant. W-b law narrows constantly and it is now critical to advise employees to take no action as a purported whistle-blower without the concurrence of a skilled and expert attorney fully apprised of the circumstances and details of that employee's employment that, in fact, those laws will be applicable.
It also bears noting that employees often think they have discovered "lying" by a supervisor or manager when they have not discovered such misconduct. In many instances, the employee at a subordinate level does not have the full info as to what subjective criteria or leeway the manager or reporting supervisor has been given by the next level up. Reporting a manager or supervisor for lying and then finding out that the employer has previously approved the definitions and methods for reported info from that supervisor, is a quick and reliable way to find oneself looking for a new job, without a reference. And that will not enable a legal claim wrongful termination.
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