The aim of this study, commissioned by the Ministry of Women's Affairs, was to assess attrition in relation to adult sexual violation cases: what proportion and type of cases drop out at each stage of the criminal justice process.
The aim of this study was to assess attrition in relation to adult sexual violation cases – that is, what proportion and type of cases drop out at each stage of the criminal justice process. Understanding the rate of attrition and reasons for attrition at each stage of the process is a critical first step towards improving policy and practice such that attrition is minimised and outcomes for victims and society are improved.
In summary, this study examined the attrition of sexual violation cases from recording of the offence by the police to final outcome. The study was based on all 1,955 cases recorded as sexual violation by the police over a 30-month period, making it the largest study in New Zealand and one of the larger studies undertaken anywhere. This study was also distinctive in that it was a nationally representative sample and in that it examined the factors associated with each stage of attrition.
Generally, the results appeared consistent with international studies, although valid comparisons were complicated by differences in definition, methodology and criminal justice processes.
The key results in relation to attrition were that:
• attrition rates were high – only 13% of cases resulted in a conviction for sexual violation
• the majority of attrition occurred during the investigation phase – charges were laid in just under a third of cases
• a third of cases were classified by the police as ‘no offence’ (including 8 percent where the complainant was charged or warned for making a false complaint), although at least some of these did appear to be offences based on the available information
• at least one in five cases did not proceed due to victim withdrawal
• attrition rates varied between cases, depending on factors such as the number and type of offences, the relationship between the victim and offender, the age and mental state of the victim, the criminal history of the offender and aggravating circumstances of the offending
• the effect of some factors, especially the victim-offender relationship, differed between stages of the justice process.
A significant limitation of the analysis was the lack of data on some potentially important variables and substantial levels of missing data for other key factors. All data were derived from a data set that summarised the available file information stored on the police NIA database, which meant the available information provided only a narrow perspective on the complex set of circumstances that make up each incident.