[4][5][6] The Mongrel Mob's primary rival is the Black Power gang, and their longstanding feud has resulted in numerous public and violent clashes over the years.

Both gangs have a significant presence in New Zealand's criminal underworld, with the Mongrel Mob being one of the most notorious and widely recognised both at home and abroad.

Legend within the gang holds that the name originated from the comments of a judge in the Hastings District Court, who referred to a group of men before him as mongrels.

[32] Joseph 'Junior' Wiringi and most of the chapter's top hierarchy were arrested in 2003 as part of the police investigation on more than 70 charges, including dealing in methamphetamine and magic mushrooms and possessing firearms.

[34] As well as undertaking 8 search warrants in the Wellington region, the Operation also targeted a property in the East Auckland suburb of Howick where the Mongrel Mob is suspected of importing the methamphetamine.

[34] The second day of the raids led to 7 arrests, as well as grenades, money, 2 kilograms of methamphetamine, locked safes, and 11 guns being found and confiscated.

[35] The six-month-long investigation involved over 300 New Zealand Police staff, including the Auckland-based National Organised Crime Group, Tauranga-based Armed Offenders Squads, and the locally based Asset Recovery Unit.

[35] The investigation proved the community concern to be accurate, and led to the arrests of over 30 members, and associates, of the Mongrel Mob Kawerau.

[39] In 2005, the Mongrel Mob Notorious chapter and its President Roy Dunn started a labour-hire business to do painting, demolition, and other work.

In 2010, Dunn and his Māngere-based Notorious chapter announced the Hauora Programme partnership with the Salvation Army to combat methamphetamine drug use.

The scheme is run by the charity Hard2Reach which aims to address trauma and drug abuse through a live-in marae based in Waipawa using funds from criminal proceeds that had been seized by the Police.

The Government's support for the Kahukura scheme was criticised by the opposition National Party leader Judith Collins and Simeon Brown, Sensible Sentencing Trust co-leader Darroch Ball, and mental health advocate Mike King.