Age Discrimination in Employment Act
The Age Discrimination in Employment Act of 1967, Pub. L. No. 90-202Code, 29 U.S.C. § 621 through 29 U.S.C. § 634 (ADEA), forbids employment discrimination against anyone at least 40 years of age in the United States (see 29 U.S.C. § 631(a)). The bill was signed into law in 1967 by President Lyndon B. Johnson.
Scope of protection 
The ADEA includes a broad ban against age discrimination and also specifically prohibits:
- Discrimination in hiring, promotions, wages, or termination of employment and layoffs.
- Statements or specifications in job notices or advertisements of age preference and limitations.
- Denial of benefits to older employees. An employer may reduce benefits based on age only if the cost of providing the reduced benefits to older workers is the same as the cost of providing full benefits to younger workers.
- Since 1986 it has prohibited mandatory retirement in most sectors, with phased elimination of mandatory retirement for tenured workers, such as college professors, in 1993.
Mandatory retirement based on age is permitted for:
- Executives over age 65 in high policy-making positions who are entitled to a pension over a minimum yearly amount.
Creation and amendments 
Written in 1961, the Age Discrimination in Employment Act of 1967, Pub. L. No. 90-202, 81 Stat. 602 (Dec. 15, 1967), codified as Chapter 14 of Title 29 of the United States Code, 29 U.S.C. § 621 through 29 U.S.C. § 634 (ADEA), prohibits employment discrimination against persons 40 years of age or older in the United States (see 29 U.S.C. § 631(a)). It also applied to standards for pensions and benefits provided by employers and requires that information about the needs of older workers be provided to the general public.
Case law 
The ADEA differs from the Civil Rights Act in that the ADEA applies to employers of 20 or more employees (see 29 U.S.C. § 630(b)) rather than 15 or more employees. Both acts do, however, only apply to employers in industries affecting interstate commerce. The 20 employees can include overseas employees Morelli v. Cedel (2nd Cir. 1998) 141 F3d 39, 45.
The ADEA protects US citizens working for US employers operating abroad except where it would violate the laws of that country - ADEA 29 USC §§623(f)(1), per Mahoney v. RFE/RL, Inc (DC Cir. 1994) 47 F3d 447, 449.
An age limit may be legally specified in the circumstance where age has been shown to be a "bona fide occupational qualifications reasonably necessary to the normal operation of the particular business" (BFOQ) (see 29 U.S.C. § 623(f)(1)). In practice, BFOQs for age are limited to the obvious (hiring a young actor to play a young character in a movie) or when public safety is at stake (for example, in the case of age limits for pilots and bus drivers).
The ADEA does not stop an employer from favoring an older employee over a younger one, even when the younger one is over 40 years old. General Dynamics Land Sys., Inc. v. Cline, 540 U.S. 581 (2004).
The United States Supreme Court in Meacham v. Knolls Atomic Power Lab, 554 U.S. 84 (2008), held that the employer, not the employee, bears the burden of proving that a layoff or other action that hurts older workers more than others was based not on age but on some other “reasonable factor.” 
The 2008 U.S. Supreme Court ruling Gomez-Perez v. Potter allowed federal workers who experience retaliation as a result of reporting age discrimination under the law to sue for damages.
In Kimel v. Florida Bd. of Regents, 528 U.S. 62 (2000), the U.S. Supreme Court held that state employees cannot sue states for monetary damages under the ADEA in federal court. The EEOC may still enforce the ADEA against states, and state employees may still sue state officials for declaratory and injunctive relief.
ADEA remedies include reinstatement and back pay for employee or damages if reinstatement is not feasible and/or employer's violation is intentional.
Section 623 of the Age Discrimination in Employment Act discusses the defenses to ADEA claims as follows:
- Employers may enforce waivers of age discrimination claims made without EEOC or court approval if the waiver is "knowing or voluntary." Blakeney v. Lomas Information Systems, Inc. (5th Cir. 1995) 65 F3d 482, 484.
- Valid arbitration agreements between employers and employees covering the dispute are subject to compulsory arbitration and no court action can be brought. Gilmer v. Interstate/Johnson Lane Corporation (1991) 500 US 20, 26, 111 S.Ct. 1647, 1652.
- Employers can discharge or discipline an employee for "good cause," regardless of the employee's age.
- Employers can take an action based on "reasonable factors other than age."
- Bona fide occupational qualifications, seniority systems, employee benefit or early retirement plans.
- Voluntary early retirement incentives.
- Greenhouse, Linda (June 20, 2008). "A Supreme Court Victory for Older Workers". New York Times. Retrieved March 1, 2012.
- Feder, Jody. "The Age Discrimination in Employment Act (ADEA): A Legal Overview". Congressional Research Service, June 23, 2010, p. 2. Retrieved 3 November 2011.
- Text of the Age Discrimination in Employment Act of 1967
- Fighting Ageism, Through the Ages
- Synopses of Age Discrimination Law Cases (Free Registration Required)
- Age Discrimination in Employment Act (ADEA) - information