Are you being sarcastic?
At least in the US, you aren't allowed to discriminate based on a protected class(race, religion, sex, age, physical/mental handicap) but iq isn't a protected class.
To be clear, while not outright forbidden, the IQ tests are instead called "personality tests" or "aptitude tests" or "coding interviews" because of this landmine legal vaguery (for example, you mentioned mental handicap -- i.e. lower IQ score -- as a protected class).