The case can be made that discriminating against an individual in the workplace because of the person’s gender, race, religion, and similar characteristics is something of a behavioral aberration that is not a part of human nature—or at least most people would like to think that is the case. But what about the scenario in which a manager takes it out on an employee who has sued or threatened to sue the employer (and maybe the manager, too) for some type of discrimination? Such retaliation may not spring from the most noble of instincts, but it is rooted in common human emotions.

Psychological theorizing aside, the fact is that retaliation claims brought against employers have become the single largest type of claim filed with the federal Equal Employment Opportunity Commission.

Whether grounded in a statute or court-made law, practically any recognized form of employment discrimination is accompanied by a prohibition against any form of retaliation against the person who has complained of the discrimination. Until recently, the claim for a prohibited form of discrimination typically was the main act, with a retaliation claim sometimes thrown in for good measure, and maybe even as an afterthought. However, retaliation claims increasingly are taking center stage.

Recent U.S. Supreme Court cases have stimulated the filing of more such claims. In 2009, the Court broadly construed the anti-retaliation provision in Title VII of the Civil Rights Act of 1964 as protecting workers who answer questions as part of an internal investigation by the employer, even though the statute uses an arguably narrower term in prohibiting retaliation for “opposing” unlawful employer practices. According to the Court, the verb “oppose” extends beyond active, consistent behavior. For example, it would be “opposition” if an employee took a stand against an employer’s discriminatory practices not by instigating an action, but by standing pat and refusing to follow a supervisor’s order to fire a subordinate worker for discriminatory reasons.

A prudent employer should take some basic measures to reduce the chances of liability for retaliation. Adopt a written anti-retaliation policy. Train managers in how to respond to complaints of discrimination. Document all investigations of employee complaints clearly and thoroughly. Finally, keep complaints of prohibited discrimination confidential, not as fair game for water-cooler conversations—a supervisor who does not even know about a complaint of discrimination cannot take action in retaliation for that complaint.