The United States Supreme Court has recently issued several rulings that carry profound implications for the Age Discrimination in Employment Act (ADEA), reshaping how age discrimination claims are litigated and interpreted in workplaces across the country. These decisions clarify critical legal standards, from the burden of proof to the scope of protected activities, and they affect both employers’ compliance obligations and employees’ rights. Understanding these developments is essential for anyone navigating age-related employment disputes or seeking to build a compliant, equitable workplace culture.

Background of the Age Discrimination in Employment Act

Enacted in 1967, the ADEA prohibits employment discrimination against individuals who are 40 years of age or older. The law applies to private employers with 20 or more employees, as well as to federal, state, and local governments. Its core purpose is to promote the employment of older workers based on their ability rather than age and to prohibit arbitrary age discrimination in hiring, firing, compensation, promotions, and other terms and conditions of employment.

The ADEA is enforced by the Equal Employment Opportunity Commission (EEOC), which investigates charges and may litigate on behalf of aggrieved individuals. Unlike Title VII of the Civil Rights Act, the ADEA has unique features, including a more demanding standard for proving discrimination and specific exemptions for bona fide occupational qualifications (BFOQs) and seniority systems. Over the decades, the Supreme Court has issued a series of rulings that refine how the ADEA is applied, and recent decisions continue that tradition of clarification.

Evolution of Age Discrimination Protections

Since its passage, the ADEA has been interpreted through landmark decisions. For example, in Western Air Lines, Inc. v. Criswell (1985), the Court upheld the requirement that employers prove a BFOQ is reasonably necessary to the normal operation of the business. More recently, Gross v. FBL Financial Services, Inc. (2009) fundamentally altered the burden of proof in ADEA cases, requiring plaintiffs to show that age was the “but-for” cause of the adverse employment action, not merely a motivating factor. That decision sharply limited mixed-motive claims under the ADEA, setting it apart from Title VII.

The 2019 case Babb v. Wilkie further addressed the standard for federal employees, holding that a federal employee must prove that age was a but-for cause of a personnel action in order to receive remedies such as money damages, but for non-personnel actions (like hostile work environment claims) the standard may be lower. In 2020, the Court in Muldrow v. City of St. Louis addressed a different question — whether a transfer without a change in title or pay could be actionable — though that case concerned Title VII, it influences the broader understanding of adverse actions.

Key Recent Supreme Court Decisions Impacting the ADEA

The most significant recent Supreme Court rulings have focused on clarifying the burden of proof, the scope of protected activities (including retaliation), and the legal standards for demonstrating discrimination. Below are the major areas addressed by the Court.

Burden of Proof in Age Discrimination Cases

In Gross v. FBL Financial Services, Inc. (2009), the Supreme Court held that a plaintiff bringing a disparate-treatment claim under the ADEA must prove, by a preponderance of the evidence, that age was the “but-for” cause of the challenged adverse employment action. This standard is more demanding than the “motivating factor” test used in Title VII cases. The Court explicitly rejected the mixed-motive framework that applies under Title VII, meaning that even if age played a role in the decision, if the employer can show it would have taken the same action for a legitimate reason, the employee loses.

In a subsequent decision, University of Texas Southwestern Medical Center v. Nassar (2013), the Court applied a similar but-for causation standard to retaliation claims under Title VII, but the standard under the ADEA for retaliation remains an open question in some circuits. However, the Court’s trend has been toward requiring proof that age discrimination was the decisive factor, not just a contributing one.

Scope of Protected Activities and Retaliation

The ADEA includes an anti-retaliation provision that prohibits employers from punishing employees for opposing discriminatory practices or participating in investigations or proceedings under the Act. In Gomez-Perez v. Potter (2008), the Supreme Court held that federal employees have a right to sue for retaliation under the ADEA, even though the statute’s text on retaliation for federal employees is less explicit than for private-sector employees. The Court reasoned that retaliation is a form of discrimination and therefore falls within the ADEA’s prohibition.

More recently, in Babb v. Wilkie (2020), the Court clarified that a federal employee need not prove that age discrimination was the but-for cause of a non-personnel action (such as a hostile work environment) in order to establish liability; instead, a plaintiff must show that age was a motivating factor for the challenged employment practice. However, to obtain money damages or other remedies, the employee must still prove but-for causation for the ultimate personnel decision. This nuanced approach creates a complex landscape for federal employees.

Disparate Impact and the “Reasonable Factor Other Than Age” Defense

The ADEA also allows disparate-impact claims, where an employer’s facially neutral policy or practice disproportionately affects older workers. The Supreme Court in Smith v. City of Jackson, Mississippi (2005) recognized that disparate-impact claims are available under the ADEA, but with important limitations. The Court held that employers may defend such claims by showing that the challenged practice is based on a “reasonable factor other than age” (RFOA). This defense is broader than the “business necessity” standard under Title VII and makes it harder for plaintiffs to win.

In a subsequent case, Meacham v. Knolls Atomic Power Laboratory (2008), the Supreme Court clarified that once a plaintiff proves a disparate impact, the burden shifts to the employer to demonstrate that the practice is based on an RFOA. The Court also held that the RFOA defense is an affirmative one, meaning the employer bears the burden of persuasion. This interpretation preserves some of the ADEA’s teeth in impact cases but still provides significant leeway for employers.

Implications for Employers

These recent Supreme Court rulings have direct and consequential implications for employers. First, the heightened but-for causation standard in disparate-treatment cases means that employers must be especially vigilant about documenting the legitimate, non-discriminatory reasons for any adverse employment action affecting an employee over 40. A well-documented performance evaluation system, objective termination criteria, and consistent application of policies are critical to defending against age discrimination claims.

Second, the expansion of protection for retaliation and participation in proceedings means that employers cannot take adverse actions against employees who complain about age discrimination or who cooperate with EEOC investigations. Even informal complaints may be protected. Employers should ensure that their anti-retaliation policies are clear and that managers are trained not to punish or intimidate employees who raise concerns.

Third, in the context of disparate-impact claims, employers need to review neutral policies that may disproportionately harm older workers. Examples include physical fitness tests that older employees are less likely to pass, layoff criteria based on seniority (which may actually benefit older workers in some contexts, but can also harm them if used inversely), or performance metrics that inadvertently disadvantage older workers. The RFOA defense provides a path for employers to justify such policies if they are reasonable and based on factors other than age, but the burden is on the employer to prove that defense.

Practical Guidance for HR and Compliance Teams

To mitigate litigation risk, HR professionals should:

  • Conduct regular audits of employment decisions (hiring, promotion, termination) to identify any pattern of age-based disparities.
  • Document all performance-related decisions with objective, job-related reasons that are contemporaneously recorded.
  • Train managers on the nuances of the ADEA, including the prohibition against subtle stereotypes about older workers (e.g., assumptions about energy, adaptability, or technological proficiency).
  • Ensure that any reduction-in-force (RIF) selection criteria are validated to avoid disparate impact, and consider offering voluntary early retirement programs that comply with the Older Workers Benefit Protection Act (OWBPA).
  • Review employee handbooks to ensure that anti-retaliation policies explicitly cover age-related complaints and that reporting mechanisms are accessible.

Implications for Employees

For employees aged 40 and older, these Supreme Court rulings reinforce the importance of promptly reporting any suspected age discrimination. The but-for causation standard means that a plaintiff must gather strong evidence that age was the real reason for the employer’s action. This evidence might include age-related comments by decision-makers, statistical disparities, or inconsistent treatment of similarly situated younger employees.

Employees should also be aware that retaliation is unlawful, and they have the right to participate in proceedings without fear of punishment. If an employer takes an adverse action soon after an employee files a complaint or testifies, that sequence may itself be evidence of unlawful retaliation.

In cases of disparate impact, employees may challenge policies that appear neutral but actually harm older workers disproportionately. However, they should anticipate that employers will use the RFOA defense, and the burden will be on the employer to prove that the policy is reasonable and not a pretext for age discrimination.

Resources for Employees

  • EEOC Guidance: The EEOC’s Age Discrimination page provides detailed information about how to file a charge and what protections exist.
  • AARP Legal Counsel: The AARP offers resources and legal advocacy for older workers facing discrimination. Their age discrimination center provides practical advice.
  • SCOTUSblog Analysis: For in-depth legal analysis of recent Supreme Court decisions, SCOTUSblog is an excellent resource that tracks pending cases and rulings affecting the ADEA.

Looking Ahead: The Future of Age Discrimination Law

The Supreme Court’s recent rulings suggest a trajectory that continues to refine the ADEA’s standards, often making it more challenging for plaintiffs to prevail in liability and damages. However, the Court has also preserved robust protections for retaliation and has recognized the viability of disparate-impact claims, albeit with a flexible defense. Congress could amend the ADEA to align its causation standard with Title VII’s mixed-motive framework, but such legislative action appears unlikely in the near term.

Meanwhile, as the workforce ages and retirement ages rise, age discrimination claims are expected to increase. Employers that proactively foster inclusive workplaces and eliminate age-based stereotypes will be better positioned to avoid litigation and to attract and retain experienced talent. Employees, for their part, must stay informed about their rights and the evolving legal landscape. The Supreme Court’s decisions serve as a reminder that age discrimination remains a serious issue in the workplace, and the law continues to evolve to address it.

Conclusion

The recent Supreme Court decisions impacting the Age Discrimination in Employment Act underscore the importance of careful employment practices and a thorough understanding of legal standards. Both employers and employees must navigate a complex framework that balances the rights of older workers against the legitimate business judgments of employers. By staying current with these rulings and implementing sound policies, organizations can reduce legal exposure while promoting fair treatment of all workers. Ultimately, the goal of the ADEA — to root out age-based discrimination and ensure that people are evaluated on their merits, not their birth date — remains as relevant today as it was in 1967.