The ADEA prohibits an employer from discharging any individual (at least 40) or otherwise discriminating against him with respect to his compensation, terms, conditions, or privileges of employment, because of such individual’s age. An ADEA plaintiff must prove that age was the “but-for” cause of the adverse employment action. But in some ADEA cases, the employer does not discipline or fire the employee. Instead, the employee quits and then sues under the ADEA claiming “constructive discharge”–that the company effectively fired him by subjecting him to unbearable age-based harassment. A constructive discharge occurs in the extraordinary case when an employee suffers “working conditions so intolerable that a reasonable person would have felt compelled to resign.” This is a high hurdle, and some courts says that the employee must first show “working conditions even more egregious than that required for a hostile work environment claim.” Serious threats to an employee’s physical safety meet this burden, although threats of serious physical harm are only one general circumstance meeting this higher standard of harassment. It may also be sufficient if there is a repeated pattern of offensive conduct by his supervisor, retaliatory actions after he complained to human resources, and his employer’s general failure to respond despite repeated complaints.