Employees over the age of 40 are protected from discrimination and harassment based on their age, as per the Age Discrimination in Employment Act (ADEA) and the California Fair Employment and Housing Act (FEHA). Their age should not be a factor when making hiring, promotion, termination, or job task decisions.
Be careful not to let questions like “maybe he’s thinking about retiring” or “she’s overqualified for the job – too much experience” be a cover for age-based discrimination. A friendly discussion of an employee’s retirement plans (“So, what are you going to do when you retire? Move to the mountains? The beach?”), especially if it’s a topic that comes up frequently, can quickly take a turn into illegal harassment.
Making hiring, promotion, and termination decisions based on an employee’s age when the employee is YOUNGER than 40 may be acceptable. There are federal and state laws governing a minimum age for work in certain positions, which may be 16, 18, 21, or even older. It’s even in the US Constitution: people under 35 can’t be President of the United States. Some states do have laws that protect younger workers from age discrimination. Regardless of applicable laws, it is important to not let age factor into your employment decisions.