Conceptual and methodological challenges in examining the relationship between mental illness and violent behaviour and crime.

There is a longstanding view within the general population and the criminal justice system that the mentally ill are more prone than the mentally healthy to violence and. This view, however, is not fully supported by empirical research, in particular due to conceptual and methodological challenges that arise when the relationship between mental illness and crime is examined. This paper reviews such challenges, reviewing areas such as the ‘criminalisation’ of the mentally ill and the ‘psychiatrisation’ of criminals, as well as the complex problem of common factors, and the mediating impact of substance abuse. Specific methodological challenges are also reviewed, including problems with conducting longitudinal and randomised research in this area, and difficulties encountered in the sampling methods used.