It is unfortunate when employees realizes they are working in the midst of illegal activity or wrongdoing by their employer, or others at their job. It is even less fortunate when they chose to do the right thing and expose the wrong doing, but later suffer retaliation for that action.
To prove you are unfairly being retaliated against will more than likely mean proving there is no reason for the unfair demotion, reprimand, harassment or possible firing that has occurred. The employer's claim will no doubt be that their action was justified or innocent. If there is evidence either way, it should be contained in your personnel file. For instance, an employee with a perfect review, or very good past appraisals, would not usually be a candidate for demotion or firing.
Are you entitled access to your personnel file if you are no longer with the company? The short answer is yes. As of January 1, 2013, California law states that employees, both current or former, as well as their representatives do have a right to a copy of their personnel records. The records must be provided within 30 calendar days of a request being made as long as it is at a reasonable time and interval.
What is meant by "reasonable time and intervals"? Reasonable time is not specifically laid out, but interpretation by the Division of Labor Standards is that it means during normal business hours at the location where the records are kept. Regular intervals means one time a year unless there is cause to believe the personnel file may have been tampered with or altered in order to incriminate the employee.
Requests for personnel records should be made in writing, and the employer has up to 30 calendar days to make the records available. There are some documents that you may not have a right to, such as any records relating to a criminal offense investigation, reference letters, documents obtained prior to your employment, or those obtained and prepared by others as a part of a promotional examination.
An attorney or representative can help you obtain your personnel files if you believe you are being retaliated against for making a complaint or disclosing unfavorable information about someone in your company. Retaliation acts are meant to intimidate whistleblowers, who deserve not only protection, but respect for cleaning up unfair or dishonest practices.
Source: State of California Department of Industrial Relations, "Personnel files and records," accessed Nov. 24, 2015