Intellectual disability is characterised by a series of significant limitations in both intellectual functions and adaptive behaviours, which appear before the age of 18.In Criminal Law, one of the actions of forensic experts consists of assessing the degree to which these limitations affect the capacity to understand and the volitional freedom of the subject, author of a criminal act.The Spanish Criminal Code establishes that any person who is not capable of understanding the unlawfulness of a criminal act or of acting in accordance with this understanding is inimputable or lacks criminal responsibility.From all of the above, we can deduce the importance of psychiatric evaluation of people with intellectual disabilities in the criminal field.