2.0 Criminal justice system bias and amplification

It is generally understood that each stage in the criminal justice system, from apprehension through to sentencing, contains a significant degree of built-in discretion with respect to decision-making. Police officers “on the beat” exercise judgement about whether or not to detain an individual for questioning. If someone is apprehended for a possible offence, Police must also decide whether or not to arrest the person, and then later whether to proceed to prosecution. Once prosecuted, the court may or may not convict; once convicted, judges decide on appropriate sentencing options. The contents of reports, prepared by probation officers and psychologists, can also be influential in such decisions.

Once a sentence has been imposed, there still remains allowance for the exercise of discretion with respect to individuals. Parole Boards make decisions, with respect to those imprisoned, about whether part of the sentence can be served on Home Detention, or whether the offender should be granted early release. These decisions are also influenced by advice from reports prepared by officials. Probation Officers supervising community-based sentences and orders also exercise some discretion in notifying breaches of conditions, and whether recall-to-prison proceedings should be initiated. Decision-making within the custodial environment, such as security classification and programme referral, tends to be more constrained by more objective criteria such as behavioural marker events, or actuarial risk estimates.

The explanation inherent to justice system “amplification” is that systemic factors exist at one or more of these steps in the process, which serve to increase the likelihood that, relative to non-Māori, Māori will progress further into the justice system, and be dealt with more severely. Thus the amplification explanation suggests that Māori who offend (or initially are suspected of offending) are, relative to non-Māori, subject to different probabilities of discharge from, or continuation within the criminal justice system. The result of such influences would be that Māori “accumulate” in the system in disproportionate numbers.

Quantifying the degree to which bias functions as a possible influence is however highly problematic. A range of factors can influence decisions at each of the stages listed above: for example, more serious offences, a history of previous offending, responses to previous sentences, and the social circumstances of the offender, can at times be very influential. Given that there is potential for some degree of correlation between offender ethnicity and certain of these variables, reasonably sophisticated statistical analysis is required in order to understand the relative contributions made by diverse factors to outcomes. In the absence of such analysis, interpretations of apparent differences must be made with great caution.

This section therefore compares the outcomes for Māori and non-Māori offenders in apprehension, prosecution, conviction and sentencing. Data from Statistics New Zealand, New Zealand Police, Ministry of Justice, Department of Corrections and two New Zealand longitudinal cohort studies are used.

Before proceeding to review the research, it is appropriate to comment more fully on the possible contribution of population-based differences between Māori and

non-Māori as a possible explanation of higher levels of participation in crime amongst Māori. As outlined in the statistical issues section (1.1) above, the relative youthfulness of the Māori population must increase the numbers of Māori in the age groups of higher risk of criminal behaviour. Statistics New Zealand figures for 2004 record 77,000 Māori males, and 350,000 non-Māori, in the 15-29 years age bracket. However, this age group constitutes 25% of the total Māori male population, but just 20% of the non-Māori male population. This occurs partly because of the relative youthfulness of Māori arising from higher fertility rates, and shorter life expectancies (there are proportionally fewer older Māori than there are non-Māori). Thus,

population-based characteristics of Māori men, with proportionally more of them in the age group most at risk of criminal behaviour, undoubtedly accounts for part of the higher rate of criminal behaviour.

New Zealand’s imprisonment rate currently is approximately 180 per 100,000. The rate that applies specifically to Māori however is approximately 700 per 100,000. Age-standardisation of these figures changes these rates: the rate for all New Zealanders becomes 152 per 100,000, and 514 per 100,000 for Māori 1 .

Age-standardisation nevertheless shows that Māori men are 3.5 times more likely to be sentenced to imprisonment.

To get a sense of the magnitude of the age-cohort effect, using the 2004 figures above, if the portion of Māori men aged 15-29 was reduced to be the same as

non-Māori (20%), there would around 15,000 less Māori men. If all else stayed equal, that would mean approximately 20% less Māori males in each stage of the criminal justice system (currently for example, around 450 fewer men in prison). So this factor explains some of the disproportionate number of Māori men in prison, but the disproportionality is still much greater than age factors can account for.

1 Nadesu, Arul (2003), A way of measuring social inequality by age standardised imprisonment rates unpublished paper, Department of Corrections, Wellington, NZ.