The relationship between crime and criminal justice is a bit like the relationship between health and medicine. What makes people healthy? Genetic legacy is important, as well as (in the most general sense) environment: the quality of the air that people breathe, the water that they drink, the food they eat; their capacity to find adequate shelter and protection from harm; their style of life; their avoidance of harmful circumstances. But most of this is entirely beyond the reach of medicine. This by no means entails that medicine is unimportant. On the contrary, high quality medical services are essential when people are ill or injured, and medical research has helped us to understand many of the elements of a healthy life. But it does expose the limitations of medical services in ensuring our health.
In a very similar way, authoritative research into the personal and social characteristics of offenders and of the influences that appear to be associated with offending across the life course draw attention to the influence of parents and carers, of other associates, of school, as well as socio-economic factors, notably poverty and limited access to resources and opportunities (social exclusion). (Some would also want to consider genetic influences on offending, as well as bio-chemical factors, diet and other factors that make a difference to our physiology – for example, lead in petrol).
Most of the factors that are known to be associated with offending, though, are entirely beyond the reach of criminal justice. Criminological research points policy towards a range of social and educational measures, but very few of these are criminal justice interventions. This does not mean that criminal justice is unimportant: on the contrary, trustworthy and effective criminal justice institutions are valuable in their own right and can make a decisive difference for many people. But, just as it is unrealistic to expect that medical services can make people healthy, so it is not reasonable to suppose that the agencies of criminal justice can solve the problems of crime. Policing activities are a modest, though important, component of crime reduction; the contribution of punishment and the penal system is even more limited.