The cutoff for discrimination is 40. It is perfectly legal (at least at the federal level) to discriminate against someone for being 39. That seems to imply t

The cutoff for discrimination is 40. It is perfectly legal (at least at the federal level) to discriminate against someone for being 39. That seems to imply that mental development is not a consideration here. The law is pretty clearly "don't discriminate against older people" rather than "don't discriminate based on age". Also for all the other comments mentioning experience. Decisions based on experience are not discrimination because experience is pertinent to one's effectiveness in a job. It isn't discrimination if an NFL team decides not to hire a disabled player because the job of being a football player has strict physical requirements. It doesn't matter that the player's disability might normally qualify as a protected class in another line of work. It isn't discrimination because the job requires that selection criteria.