BACKGROUND: Excellence is that quality that drives continuously improving outcomes for patients. Excellence must be measurable. We set out to measure excellence in forensic mental health services according to four levels of organisation and complexity (basic, standard, progressive and excellent) across seven domains: values and rights; clinical organisation; consistency; timescale; specialisation; routine outcome measures; research and development.

AIMS: To validate the psychometric properties of a measurement scale to test which objective features of forensic services might relate to excellence: for example, university linkages, service size and integrated patient pathways across levels of therapeutic security.

METHOD: A survey instrument was devised by a modified Delphi process. Forensic leads, either clinical or academic, in 48 forensic services across 5 jurisdictions completed the questionnaire.

RESULTS: Regression analysis found that the number of security levels, linked patient pathways, number of in-patient teams and joint university appointments predicted total excellence score.

CONCLUSIONS: Larger services organised according to stratified therapeutic security and with strong university and research links scored higher on this measure of excellence. A weakness is that these were self-ratings. Reliability could be improved with peer review and with objective measures such as quality and quantity of research output. For the future, studies are needed of the determinants of other objective measures of better outcomes for patients, including shorter lengths of stay, reduced recidivism and readmission, and improved physical and mental health and quality of life.