Sexual Assaults

I’ve finally discovered something useful done by the Ministry of Women’s Affairs. They have published a study into why so few sexual assault complaints result in convictions, and it is full of interesting stats. The study is of 1,955 police files relating to sexual assaults upon an adult from July 2005 to Dec 2007.

68% of the files involved rape, 22% unlawful sexual connection, 7% attempted sexual violation and 3% other.


So one third of complaints are not about a valid offence. We learn that 8% were classified as false complaints, so presumably the other 26% were complaints that were not deemed to involve illegal behaviour.

Of the remaining 66% of valid offences, one sixth did not have a suspect identified which brings it down to 55%. A surprisingly high 44% of cases with an identified suspect are not prosecuted meaning 31% of all complaints result in prosecution. And of those 42% resulted in a conviction.

This means overall only 13% of complaints lead to a conviction. However the more useful figure is that 20% of “valid” complaints lead to a conviction.

So let us first look at cases not deemed valid.

‘False complaints’ were defined as cases in which the complainant was charged or warned for making a false complaint. In ‘false complaint’ cases for which further information was noted in the summary data set, the two most common file notes were that the complainant had admitted the allegation was false and that the evidence did not support the complaint. The victim had an intellectual disability or a psychiatric condition or had made previous allegations in around a third of cases.

If 8% of 1,955 cases were “false” that is 156 cases.

So what about the other cases deemed not valid:

The ‘no offence’ category accounted for 34 percent of recorded cases (including the 8 percent designated ‘false complaints’), which was lower than the 45 percent ‘no offence’ rate found in a 1981 New Zealand study (Stace, 1983).

So the category has dropped in frequency.

At least one in five cases did not proceed due to victim withdrawal. That is, the investigating officer recorded that the victim did not want to proceed with the investigation or was uncooperative or could not be contacted. Withdrawn cases were more likely than other cases to involve an offender who was an ex-partner or boyfriend. The police files noted a variety of reasons for a victim not wanting to proceed, including that the victim wanted the offender warned or trespassed but not prosecuted; someone else reported the incident or the victim was pressured to report; the victim had limited recall of the incident; the victim wanted to report the incident or seek advice but take no further action; or the victim did not feel able to proceed, was not ready to proceed or felt threatened.

It is a shame so many victims withdraw, but I can understand why. Now why do one sixth of valid cases not have an identified suspect?

The most common factors in cases with no identified suspect were that the victim withdrew from the process, there was insufficient evidence to identify a suspect who was a stranger to the victim, or the victim had limited recall due to intoxication.

So why were there no charges in 44% of cases with an identified suspect?

The prosecution rate (percentage of cases with charges laid) was 31 percent based on all recorded cases or 46 percent if ‘no offence’ cases were excluded from the base. The prosecution rate for cases involving multiple offences was much higher than for single-offence cases and thus the prosecution rate based on recorded offences (49 percent) was higher than the prosecution rate for cases (31 percent).

Cases in which a known suspect was not charged tended to involve either victim withdrawal or insufficient and/or conflicting evidence.

What is interesting is that victim withdrawal is a common factor at almost every stage. It is a major factor in cases not being deemed valid, in no suspect being identified and in no prosecution being undertaken.

I wonder what the attrition rate at each stage would be, if there was no victim withdrawal? That would be a useful piece of data.

It seems clear that the most significant way to increase the prosecution rate of sexual assaults, would be to have fewer victims withdraw. But that is easier said that done. Many victims can have very valid reasons for not wanting the trauma of a court case.

Some interesting other factors:

  • Rape cases had higher attrition rates at almost every stage of the justice process, compared with other offences.
  • The 18 percent of cases that involved more than one offence were much more likely to proceed through all stages and result in a conviction than cases involving a single offence.
  • The majority of offenders were previously known to the victim, with stranger assaults accounting for just 16 percent of cases and offenders just met (within the last 24 hours) accounting for a further 15 percent of cases.
  • A third of cases involved victims and offenders with intimate relationships
  • Attacks by a stranger were more often associated with ‘false complaints’
  • However, if prosecuted, stranger attacks were much more likely to result in a conviction, giving these cases a relatively high overall conviction rate. (this is logical, as it is harder for the defendant to claim consent if they were strangers)
  • Current partners and boyfriends had a high prosecution rate but a very low conviction rate for sexual violation (also no surprise as issues of consent much harder to determine)
  • Offenders who were family members had high prosecution and conviction rates relative to other offenders (and again this is logical as few family members ever have consensual sex)
  • Cases were more likely to be classified as ‘no offence’ if the victim was uncertain whether violation had occurred. The victim was uncertain in about one in seven cases, and this factor was strongly linked to alcohol or other drug use. (that is a disturbing stat)

They also list factors that do not affect attrition:

  • Region (except Akl City has lower level of no offence cases)
  • Victim Gender
  • Victim Ethnicity
  • Victim Origin
  • Victim Criminal History
  • Victim is a sex worker
  • Offender Gender
  • Offender Age
  • Offender Ethnicity
  • Offender Origin
  • Incident Timing

This is actually very pleasing. It would be a concern if the demographics of either the victim or offender caused a lower or higher attrition rate in terms of prosecution or conviction.

Also some interesting stats on the 31% of cases that had charges laid:

  • 16% plead guilty
  • 30% had the case withdrawn or discharged
  • 52% went to trial
  • Of those that went to trial 50.5% were acquitted and 49.5% found guilty

This is a really invaluable report, full of data. It has certainly given me a much better understanding of how the justice system deals with sexual assault complaints, and should be very useful for policy makers as they seek to improve the system.

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