It’s even easier for employees and former employees to sue businesses for retaliation under the Equal Employment Opportunity Commission’s new enforcement guidance.

For the first time since 1998, the agency has updated its guidance on the claim, which is already “asserted in nearly 45 percent of all charges … and is the most frequently alleged basis of discrimination,” it said.

Needless to say, preventing a claim is much better than defending one, and retaliation often occurs even when the underlying discrimination claim doesn’t have merit. So businesses must take action to avoid retaliation in the first place.

The guidance clarifies the definition of what actions by employees are protected from retaliation, integrating seven related U.S. Supreme Court decisions issued on the topic over the past 18 years.

“Protected activities” include an employee’s participation in an employment case against the business or “reasonably opposing” illegal conduct by the business. That means a business can’t punish an employee or job applicant for stating his or her disagreement with possible discrimination violations. And that may include complaints about things the business does that could become discriminatory.

The guidance also makes clear that the list of actions considered retaliation is long, and includes disparaging the person to others or in the media and threatening reassignment, among others.

The rub for businesses is that nearly anything could be considered a “protected activity” or retaliation. To help businesses comply, the EEOC has laid out some best practices it recommends.

Now is a good time to review your policies to ensure you’re following these suggestions:

• Be sure to have a written non-retaliation policy: Your policy should include examples of what to do and what not to do, as well as ways to avoid retaliation. Include a requirement to report “perceived” retaliation, noting that any retaliation will lead to disciplinary action. If your retaliation policy is mixed into your other policies, that might still meet the standard. But you must ensure that these elements are clear.

• Train all employees and supervisors on retaliation: In your annual harassment training, require separate training on the policy surrounding retaliation and how to avoid it. Provide ways to report any possible retaliation. For managers, give guidance on avoiding any actions that could be construed as retaliation.

• Have a procedure in place for proactive follow-up after any retaliation complaint: Speak with both the employee and his or her manager to assess the situation in a timely manner after any complaint is raised and address issues as they come up.

• Review all employment actions to ensure compliance: Have someone involved in human resources pay close attention to any changes related to a complaining employee, such as performance evaluations or pay changes.