Michael Laws, the former mayor of Whanganui who pushed for a localised gang patch ban, says it led to a decrease in gang membership in his region.
“Whanganui is where your evidence is to answer all the questions that have been posed," he said.
"There was a 15% reduction in gang membership and gang association as a result of the bylaw, there were less gang-on-gang encounters."
Laws said the reduction was due to people leaving gangs, and also leaving Whanganui.
The Wanganui District Council (Prohibition of Gang Insignia) Bill was a controversial measure. In 2011, the High Court ruled that the council’s bylaw to ban gang patches in public areas was unlawful, invalid and inconsistent with the Bill of Rights Act.
Former National Party minister and Whanganui MP Chester Borrows, who helped the bill become law, said it had been ineffectual in practice.
“Anything that allows police to harass gangs and stop them going about the illegal intimidatory ways is a good thing," he said.