Wanganui's anti-gang-patch bylaw has been ruled unlawful by the High Court after a challenge by the Hell's Angels.

Hell's Angels member Philip Ernest Schubert of Auckland challenged the Wanganui District Council bylaw banning people wearing gang insignia in public.

The bylaw, which came into force on September 1, 2009, bans the patches, insignia and colours of 10 gangs in public places in Wanganui, Mowhanau, Kai Iwi and rural community halls.

Gang members breaching the ban can be fined $2000 and have the insignia confiscated.

In a ruling issued yesterday, Justice Denis Clifford said the ban was not lawful because it covered such a wide area and the council had not considered all the issues related to the right of freedom of expression.

Last night, former mayor Michael Laws, who introduced the bylaw, said he had not read the full judgment but the High Court was wrong in fact.

Mr Laws said the ban covered only 10 per cent of the district, and the council had considered freedom of expression issues.

He said the council had two options - appeal against the ruling or amend the bylaw.

The court had upheld the right of the council to create a bylaw to ban gang patches, and that was the most important finding.

"It will be for my council colleagues to choose which course they will adopt but the gang-patch ban is here to stay," Mr Laws said.

Wanganui District councillor Rangi Wills said the gang-patch ban had curtailed public intimidation by gang members and quietened things down in the city.

Last year, when Mr Schubert applied for a judicial review of the ban, his lawyers described the bylaw as a "sledgehammer used to crack a nut".

Lawyers Steven Rollo and Duncan Webb, from the Christchurch firm of Lane Neave, told the court the geographical area the bylaw covered was too vast in its scope and amounted to prohibition throughout the district.

Mr Webb said the definition of the types of insignia banned under the bylaw was "hugely broad and vague" for the geographical area it covered, and said the wider area would be permissible if a narrower scope for the insignia were given.

The ban was basically prohibition, which breached the Bill of Rights Act, and Parliament hadn't given the council the power to do this, Mr Webb said.

Last month, the Whangarei District Council said it planned to meet police to examine the possibility of banning gang patches from the central city.

Police area commander Inspector Paul Dimery said Northland was seen as a "cash cow" by gangs, particularly through the manufacture and distribution of methamphetamine.

In his monthly report to the council, he said it was "time to be brave and put a mark in the sand", and suggested the council look at a bylaw banning the patches.