The equal protection clause of the U.S. Constitution requires that laws apply equally to all citizens. Some employees have successfully challenged adverse employment actions under the equal protection clause even when the employee has not been able to successfully argue that he/she was discriminated against due to membership in a protected class. These employees put forth the legal theory that they were treated differently than similarly situated colleagues simply for arbitrary or vindictive reasons. In other words, the employee should be treated as a protected "class of one."

In Engquist v. Oregon Dept. of Agriculture, 128 S. Ct. 2146 (2008) an employee who whose job was eliminated during reorganization after she had complained about one of her supervisors made exactly this argument. The jury found in the employer's favor on the employee's race, gender and national origin claims. However, the jury ruled in favor of Engquist on her equal protection claim under the "class of one" theory, awarding her $175,000 in compensatory damages and $250,000 in punitive damages. The 9th Circuit Court of Appeals ruled that a public employee could not maintain a "class of one" equal protection claim.

On appeal, the U.S. Supreme Court determined that there should be a different analysis when a government acts as a regulator, which is the area that most equal protection claims are raised, than when it acts as an employer. Borrowing from prior 1stAmendment cases the Court stated that there is a "common sense realization that government offices could not function if every employment decision became a constitutional matter." Id. at 2148. The Court concluded that the equal protection clause does not require that there be judicial supervision of every exercise of managerial discretion by a public employer.

This case is significant because it means that employees will now have to prove discrimination based on membership in a protected class and can no longer rely on the equal protection clause as an independent cause of action in discrimination cases. The language in this case may be extended to other claims of employment discrimination where a public employer claims that its decision should be given deference by the Courts.