The EEOC website provides the following definition: "Retaliation occurs when an employer takes a materially adverse action because an applicant or employee asserts rights protected by the EEO laws. Asserting EEO rights is called 'protected activity.'"

The EEOC was created to enforce the rights granted under Title VII of the Civil Rights Act of 1964, but since that date, its authority has been extended to cover other rights guaranteed by additional pieces of legislation such as the Age Discrimination in Employment Act (ADEA), the Americans with Disabilities Act (ADA), the Equal Pay Act (EPA), the Genetic Information Nondiscrimination Act (GINA), among others.

Generally, "protected activity" is either participating in an EEO process or reasonably opposing conduct made unlawful by an EEO law. Protected activities thus include:

• Filing a charge of discrimination with the EEOC, or being a witness in a filed charge
• Reporting acts of discrimination (including harassment) to a supervisor
• Answering questions during an investigation of alleged harassment
• Refusing to follow orders that would result in discrimination
• Resisting sexual advances, or siding with others to protect them against such advances
• Requesting accommodation for a disability or religious practice
• Asking others (including managers) about wages in an effort to disclose discriminatory salary practices

Here are some situations the EEOC considers to be a "materially adverse action:"

• Reprimanding the employee or giving an unwarranted performance review, or one that is lower than what is deserved
• Suspending or discharging the employee
• Transferring the employee to a less-desirable position
• Engaging in verbal or physical abuse
• Removing supervisorial responsibilities
• Threatening to report the employee to authorities (or actually doing so) over matters like immigration status
• Increasing scrutiny of the employee
• Spreading false rumors
• Making the person's work more difficult (such as changing work hours)

Employers, however, are still free to discipline or discharge employees for performance issues so long as they are non-retaliatory and non-discriminatory actions. The EEOC states: "Even though the anti-retaliation laws are very broad, employers remain free to discipline or terminate employees for poor performance or improper behavior, even if the employee made an EEO complaint." The employee must prove that the adverse action was taken in response to engaging in a protected EEO activity for a charge of retaliation to stick.

The U.S. Supreme Court has held that, in cases involving private employers, the materially adverse action must be shown to be "but for." In other words, though other factors may have been involved in the adverse action, retaliation was the deciding component. "But for" retaliation, the action wouldn't have taken place.

The types of evidence needed to prove retaliation include, among others:

• Suspiciously close timing between the materially adverse action and the EEO activity
• Oral or written statements showing a retaliatory motive or contradiction in motive - for instance, showing that the disciplinary action was not used against others with the same alleged infraction
• Showing the falsity of the employer's stated reasons for the adverse action

The Occupational Safety and Health Administration (OSHA), a division within the Department of Labor, oversees 20-plus national laws protecting the rights of employees to "blow the whistle" on illegal or unsafe practices of employers.

The laws it oversees include not only the Occupational Safety and Health Act, which sets standards for health and safety in the workplace, but also federal legislation concerning waste disposal, toxic substances, clean air, asbestos hazards, money laundering, pipeline safety, and even the Affordable Care Act, among others.