On Jim Mora's Panel (Radio New Zealand) a fortnight ago I mentioned a case which higlighted the contrast between the efficiency of criminal justice in 1967 and today. A Radio New Zealand reporter told me that Convery/Cowley had been convicted and sentenced within 2 months of the murder of his five year old victim. A typical case today would take over 10 times as long.

The discussion also touched on the huge increase in crime rates since 1967.

 IIt is quite true that murder rates have fallen, since the peaks of the 1990s. Some of that fall is in line with falls in many countries overseas (not perhaps the UK). But there are significant differences for New Zealand's crime rate patterns. The most worrying is the persistence, indeed increase, of serious violent crime among young people.

Jim (and I) I got emails challenging the notion that crime is more serious today than in the past. One referred me to a 2009 Herald article by Simon Collins, stating that we'd had a steep fall in our murder rate. It cited material apparently given to Mr Collins by the Victoria University Institute of Criminology. Among other figures the article claimed that our annual murder rate from 1926 to 1970 was 6 per million people. 

 I wrote to Herald writer Simon Collins because I could not reconcile figures in his report with what I know of Justice Dept statistics.

"I'm intrigued by your piece on the murder rate. I wonder whether whoever supplied your figures decided to simplify definitions without mentioning it to you. I can understand that because some people prefer to work on culpable homicide figures (excluding traffic accidents) instead of murder, to avoid the effects of things like shifts in convictions between murder and manslaughter. Some too try to adjust for insanity killings (where there will be no conviction) attributing some relatively standard ratio to adjust the conviction figures.

But even with all those allowances I cannot see how your table figure of 1926 – 1970 = 6 murders per million of population was derived for New Zealand. Indeed if the table is for culpable homicide then it appears grossly to understate the figures for more recent periods.

The 1968 Government book "Crime in New Zealand" states (page 23) that from 1920 to 1966 105 persons were found guilty of murder, an average of 2.2 per annum. Total deaths by violence reported to the Police over 60 years up to 1966 rose from 66 per decade before the first world war to 107 in the ten years up to 1966. Note that – per decade! That is just over 10 per year. It is hard to see on any measure how the article's reported figure per million was derived.

The "Crime in New Zealand" book was the Hanan (Minister) and Robson (Secretary of Justice) attempt to educate the public with facts, to justify their planned (and carried out) scheme to transform what they regarded as an unnecessarily punitive criminal justice system, but I've seen nothing to indicate any warping or fiddling with the figures in it.

Accordingly I'm curious about the accuracy of other statements in the article."

 I did not explain more in the note to Simon, because he is a good journalist. He's followed crime rate issues for many years. I think that when he has time he'll follow up and check himself. Perhaps the VUW Institute of Criminology led him astray. I've not found them to be objective or helpful.

I've tried to think of reasons for the discrepancy. Other adjustments to the reported "death by violence" figures that can influence the significance of changes in the murder conviction rate include insanity killings and killings by suspects who commit suicide, so do not stand trial.

Over the long period up to the mid 1960s the rate of insanity killings averaged a little under half of those for murder. The adjustment for suspects who commit suicide is not specified. It was lower than the insanity killing rate, but it may have been higher than today, because suicide was a rational reaction when the penalty for murder was hanging. Typically it seems that murders are less than one third of the reported deaths by violence.

 I focussed on the earliest figures in Simon Collins' article simply because I had the book Crime in New Zealand handy in my bookshelf at the office, but I'm puzzled by other figures reported as well. I hope he has another look at what the VUW academics gave him.