The United States Supreme Court decision in Gross v. FBL Financial Services, Inc. creates a rift between the treatment of so called "mixed-motive" cases under the ADEA and Title VII. Under Title VII, an employee may allege that he suffered an adverse employment action because of both permissible and impermissible considerations—i.e., a “mixed-motives” case. If a Title VII plaintiff shows that discrimination was a “motivating” or a “ substantial” factor in the employer’s action, the burden of persuasion shifts to the employer to show that it would have taken the same action regardless of that impermissible consideration.
The Supreme Court declined to apply the mixed-motive burden shifting to ADEA cases holding that a plaintiff bringing an ADEA disparate-treatment claim must prove, by a preponderance of the evidence, that age was the “but-for” cause of the challenged adverse employment action. The burden of persuasion does not shift to the employer to show that it would have taken the action regardless of age, even when a plaintiff has produced some evidence that age was one motivating factor in that decision.
Congress amended Title VII to explicitly authorize discrimination claims where an improper consideration was “a motivating factor” for the adverse action, see 42 U. S. C. §§2000e–2(m) and 2000e–5(g)(2)(B),while leaving the ADEA language unchanged. The Supreme Court viewed this omission as a congressional policy statement and declined to recognize the so called "mixed motive" analysis in ADEA claims. However the Courts’ opinion invites Congress to fix the discrepancy by legislatively negating the Court’s decision much like it did in with both the ADA Amendments Act and the Ledbetter Fair Pay Act:
Unlike Title VII, the ADEA’s text does not provide that a plaintiff may establish discrimination by showing that age was simply a motivating factor. Moreover, Congress neglected to add such a provision to the ADEA when it amended Title VII to add §§2000e–2(m) and 2000e–5(g)(2)(B), even though it contemporaneously amended the ADEA in several ways, see Civil Rights Act of 1991, §115, 105 Stat. 1079; id., §302, at 1088.
Expect Congress to harmonize the treatment of Title VII and ADEA claims so that the mixed motive analysis applies to both. Congress should really fix the differentiation between age discrimination cases and other discrimination claims. For some reason unknown to me, Congress placed protections from age discrimination in the Fair Labor Standards Act (governing topics like minimum wage and overtime) rather than just adding "age" to the list of Title VII’s protected classifications. As a result, federal age discrimination claims have different rights, procedures, and damages.