By Maggie Tait of NZPA

Wellington, May 27 NZPA - "Three strikes" legislation may have the opposite effect to its intention should criminals decide to kill witnesses rather than face severe punishment, MPs were told today.

New Zealand Law Society criminal law subcommittee convenor Jonathan Krebs was asked to reappear before the law and order select committee today after running out of time at a previous session.

The committee is considering the Sentencing and Parole Reform Bill which includes ACT's three strikes policy under which offenders would be locked away for life for the third serious offence that carried a five year or longer sentence.

The bill also makes it more difficult for the worst violent offenders to get parole.

"Rather than be a deterrent it is in fact, in some cases, an encouragement for people facing their third strike sentence to avoid conviction and punishment by minimising the number of witnesses which were available to give evidence against them," Mr Krebs told MPs.

He said research showed that "the three strike rule would not have a deterrent effect, it would in fact have a very deleterious effect on society by encouraging offenders to take out witnesses rather than leave them there. There's evidence of that."

ACT MP David Garrett said the research was arguable and there were other papers that said the opposite.

Mr Krebs repeated his concerns that the policy removed judicial discretion and in effect allowed police to determine sentencing as they chose what charges to lay.

The society thought the policy constituted "cruel and disproportionately severe treatment or punishment" and breached the Bill of Rights Act.

It said the threshold to avoid having the mandatory sentences apply was too high.

The regime could constitute inhuman treatment under international agreements because of the courts nor parole board would be allowed to consider individual circumstances.

Mr Krebs said there was no need for the bill and preventive detention was a better option and already available.

NZPA