Mental retardation is a term for a pattern of persistently slow learning of basic motor and language skills during childhood and a significantly below-normal global intellectual capacity as an adult. One common criterion for the diagnosis of mental retardation is a tested intelligence quotient (IQ) of 70 or below. In England and Wales the Mental Health Act 1983 defines mental impairment and severe mental impairment as a state of arrested or incomplete development of mind which includes significant/severe impairment of intelligence and social functioning and is associated with abnormally aggressive or seriously irresponsible conduct on the part of the person concerned. As behavior is involved, these are not necessarily permanent conditions: they are defined for the purpose of authorizing detention in hospital or guardianship. Unfortunately, English statute law uses mental impairment elsewhere in a less well-defined manner implying that mental retardation is meant.