[header] How to prove age discrimination in hiring [title] Read up on federal law. [step] Federal law prohibits discrimination in hiring on the basis of age when the applicant is 40 or older. The primary motive for refusing to hire someone must have been age. 
In other words, there cannot be other legitimate reasons mixed in for refusing to hire someone (such as not wanting to pay a higher salary for a more experienced applicant). [substeps] Federal law does not apply to all employers.