The Sensible Sentencing Trust has been criticised for its response to the fatal police shooting north of Auckland.
A 29 year-old man was shot dead by officers in the early hours of Saturday morning after he approached with a machete.
Trust spokesman Garth McVicar wrote on Facebook: "One less to clog the prisons! Congratulations to the New Zealand Police, our thoughts are with the officer who was forced to take this action to protect the public."
Roger Brooking is the author of Flying Blind- how the justice system perpetuates crime and the corrections Department fails to correct and blogs about crime, justice and prison issues.
He said Mr McVicar’s comments are "disgusting".
"It demonstrates the depth to which he's prepared to go to just get a bit of publicity.
"The Labour Government wants to reduce the prison population so I think Garth gets the sense that his time in the sun is over and so he's just made an outrageous statement to try to get a bit of publicity," Mr Brooking said.