Should the Supreme Court approve disparate impact under the Age Discrimination in Employment Act of 1967? The issue is presently before the Court on writ of certiorari, and this article primarily contains new arguments and evidence, both pro and con, on the issue. 1. Justice Powell's Theorem. PRO: Justice Powell theorized in Connecticut v. Teal that disparate treatment and disparate impact are not separate claims, but rather methods of proving the single claim of discrimination. He offered no proof for this theorem, but analysis reveals that he was right. By examining disparate treatment and disparate impact in light of the elements of claim of discrimination, we find these methods of proof differ only in the ways they prove causation. Both prove that a protected characteristic was a cause of the employer's denial of an employment opportunity to the plaintiff; disparate treatment proves causation with evidence of intent, and disparate impact proves causation with evidence of effect. Justice Powell's theorem is no longer true of Title VII because the 1991 amendments allow for compensatory and punitive damages in cases of intentional discrimination; therefore, intent is now a material element of one of the claims under Title VII. But Justice Powell's theorem remains true of the Age Act, which was not amended in any relevant way. CON: Disparate treatment and disparate impact have always been separate claims, distinguished by whether the defendant's intent is a material fact. 2. Text of the Age Act. PRO: If Congress used the words because of age in their ordinary meaning, they comprehend two ideas of causation. One idea of causation is that a person's reason for action is a cause of the person's act; this idea corresponds to disparate treatment. The other idea of causation is that a proximate fact in the chain of facts that culminates in a reason for action is also a cause of the act; this idea corresponds to disparate impact. CON: The legislative history of the Age Act makes clear that Congress was unaware of disparate impact in 1967; the Supreme Court's error in Griggs v. Duke Power Co. should not be repeated. No representative or senator spoke of disparate impact. The report to Congress on age discrimination by the Secretary of Labor contemplated only intentional discrimination. The origin of section 4(a)(2) shows it was directed at the disparate treatment of labor union members by their unions, not at disparate impact. 3. Reasonable Factors Other Than Age. PRO: The legislative history of the defense in the RFOA clause shows it was meant to protect only job-related practices. The origin of the clause in an unsuccessful equal pay bill confirms this conclusion. CON: The legislative history of the RFOA clause shows that Congress did not understand disparate impact. The true origin of the clause is a line of bills, dating from 1958, aimed at age discrimination; none of these bills contemplated disparate impact. The article concludes with arguments and evidence, based on the purposes of the Age Act, in favor of recognizing disparate impact.