A more thorough explanation:

Mixed-motive instruction is a type of instruction used in discrimination and improper retaliation cases in courts. It is used to determine whether a defendant's action was motivated by an impermissible reason or not.

The instruction usually takes the following form: "If the plaintiff shows that the defendant did something that hurt her, and the action was motivated by an impermissible reason, there is a presumption that the defendant's conduct was wrong. The defendant may rebut this presumption by showing that it would have taken the action regardless of its impermissible motive."

For example, if an employer fired an employee because the employee was African American and also because the employee fraudulently overstated her job qualifications, the employer may not be liable for illegal racial discrimination. This is because fraudulently overstating job qualifications is a valid reason for firing someone regardless of their race. However, if the employer fired the employee because of their race and because they did not like the Yankees, the employer would likely be liable because not liking the Yankees is not a valid reason for firing someone.

There are different variations of mixed-motive instructions. Some trigger a presumption of liability if an improper motive played any part in a defendant's decision, while others require the improper motive to play a significant role in the decision. In some cases, plaintiffs must show that an improper motive was a "but-for" cause of the defendant's action.

Overall, mixed-motive instruction helps courts determine whether a defendant's action was motivated by an impermissible reason or not, and whether they should be held liable for discrimination or improper retaliation.