Lack of evidence longer sentences deter crime

Do longer prison sentences deter people from committing crimes? Any evidence is lacking.

NZH – The High Court judge’s challenge: Show me the evidence long sentences put people off committing crime

Justice Matthew Palmer told lawyers ahead of sentencing he wanted them to come to court with evidence longer sentences actually had the deterrent effect the law told him to consider.

Days later, defence lawyers came with research showing it didn’t work.

The Crown turned up with nothing.

The sentencing notes of Justice Palmer reflect concern around the lack of evidence in an area which the Sentencing Act 2002 says should be considered when judges consider how long to send people to jail.

It follows research by the Office of the Prime Minister’s Chief Science Adviser this year which studied tough-on-crime laws and found “there is no evidence of the supposed ‘deterrent’ effect of harsher sentences”.

“On the contrary, these political decisions appear to drive up the prison population and put further costs on the taxpayer.”

Annabel Maxwell-Scott, Chevonne Wellington’s lawyer, cited studies show “long sentences are not effective in deterring others or the offenders themselves”.

She produced research showing there was a higher likelihood of repeat offending for drug crimes when someone was sentenced to prison rather than non-prison sentences.

People using drugs are driven by their addictions, so the possibility of being sentenced is unlikely to deter them.

Victoria University criminologist Dr Liam Martin said the theory of deterrence argued along two strands – that the wider community was put off committing crime because of long sentences and that the individual sent to prison did not commit further crime because of the length of sentence.

He said the idea the broader community was dissuaded from criminal offending was impossible to measure.

However, he said there was a large body of evidence showing individuals were not deterred by long sentences and some studies showed those people went on to commit more crime.

However there are obviously non-drug related offences, and also other factors when considering sentences. For example if people are in prison they can’t commit crimes.


  1. Corky

     /  28th August 2018

    ”Do longer prison sentences deter people from committing crimes? Any evidence is lacking.”

    Talkback did a segment on this topic. Most crooks who rung in said initially their sentences did not deter them. However, as they matured, and especially if they had children, longer prison sentences broke them and they decided to go straight. The exception to that was people who went down for manslaughter and murder. Most said once was enough. Especially now that prisons are run by gangs. Gangs were a recurring theme.

    The way I see it. If you are in prison you aren’t committing crimes against innocent people.
    The longer the sentence, the better.

    • Gezza

       /  28th August 2018

      Mongrel Mob member murder in Whanganui: 8 arrests
      August 28, 2018 Report from RNZ

      Eight people have been charged in relation to the killing of Mongrel Mob member Kevin Ratana in Whanganui last week. Police say they found firearms and ammunition when they executed search warrants yesterday. They say those arrested are facing various charges, including threatening to kill, unlawful possession of ammunition and participation in an organised crime group. Police are continuing a homicide investigation and say they expect to lay further charges.

      Hundreds of Mongrel Mob members attended the tangi for the 27-year-old yesterday at Parikino Marae on Whanganui River Road. An increased number of armed police and the Eagle helicopter would be in the area again today, police said.

      Whanganui acting mayor Jenny Duncan told Morning Report the heavy police presence was reassuring to residents. “We would rather the police weren’t here, but given that we’ve had the event, we’re very pleased the police are here in such strong numbers.”

      Ms Duncan said a gang meeting was taking place today, which was was a positive sign they also wanted a good outcome. “If they’re meeting today that means [they] have an intention of wanting to keep the peace themselves, which is very reassuring, so we don’t expect this to go on too much longer.” In the meantime, she encouraged residents to go about their business as normal.

      Black Power gang representative Denis O’Reilly said collaborative talks between gangs was ongoing.

      From Scoop.

  2. Third Rail

     /  28th August 2018

    Interesting research reported in The Economist:

    “Harsher sentences work as a deterrent, but only up to a point…

    They found that the convicts did seem to respond to the harsher sentences. They estimated that previously convicted criminals discount the future at a rate of 0.74: in other words, they care about events in one year’s time around three quarters as much as events today. This compares to discount rates of around 0.95 more common in the population at large. The economists compare different groups; the highly educated are most sensitive to heftier sentences, while immigrants and drug-offenders are least sensitive. ”

    Perhaps the prosecution could have handed that research to the judge?

    But why is a judge demanding the prosecutor justify what has already been encoded in law?

    Isn’t this judicial activism?

    • Joe Bloggs

       /  28th August 2018

      No its called transformative justice that’s focused on rehabilitation rather than retribution.

  3. david in aus

     /  28th August 2018

    There is a segment of the population with pathological Anti-Social tendencies, coupled with violence- they are our criminals. Rehabilitation would not work with this cohort , they are beyond help. The time for intervention was in early childhood.

    We are asking the wrong question of long prison sentences as the question is framed by Left-wing handwringers. These do-gooder do not care about the cost to society of harm to future victim or even cost to the taxpayer. They have this naïve notion that we will change these psychopaths with just goodwill. Too many Kumbaya sessions.

    The question should be: Do these long prison sentences keep the community safer? Is the trade-off in prison costs worthwhile to the community.

    Undoubtedly -YES.

  4. Kitty Catkin

     /  28th August 2018

    I imagine that criminals don’t think that they will be caught, so in one sense the sentence is immaterial. People cheating in exams don’t think that they will be caught. Children don’t think that mum will know who ate the chocolate cake. The idiot who filmed himself doing 200kph on the Auckland motorway and boasting about passing on double yellow lines hadn’t thought that the police have computers and access to Facebook etc.

    In the US, the death penalty doesn’t put murderers off.