Definition from Nolo’s Plain-English Law Dictionary
In employment law, facts the employer learns after firing an employee for which the employer would have fired the employee anyway. After-acquired evidence may be used as a defense to a wrongful termination lawsuit or to limit the damages available to an employee who was wrongfully fired. For example, an employer may discover, after illegally firing an employee because of his age, that the employee stole from the employer. The employer may use this evidence to limit its damages for lost wages in an age discrimination lawsuit to what the employee would have earned between the time he was fired and the time the employer would have discovered his theft and fired him absent any age discrimination.