This paper examines the development of case law and sentencing jurisprudence in different jurisdictions with regard to sentencing offenders with a mental illness, mental condition or intellectual disability, and with specific emphasis on the position in NSW. Of particular interest is whether it has been universally accepted that a causal connection is required between the offender’s mental disorder and the offence committed before a more lenient sentence may be imposed, and whether it is appropriate to apply this same approach to the sentencing of offenders with an intellectual disability.