West Auckland gang member David Cossill, who shot as police surrounded his home, sentenced

A gang member who fired a gun into the air and threatened to kill police officers during an hours-long standoff at his West Auckland home is likely to be released from jail soon after a judge described him as "somebody that this country has failed dismally".

David Cossill, 40, who has spent much of his life in and out of state homes and prisons, eventually told authorities he was very high during the February 2021 incident and in his meth-addled mind he thought it might be good to "go out with a bang".

Auckland District Court Judge Mary-Beth Sharp sentenced him to 21-and-a-half months' imprisonment on Friday for a charge of using a firearm against a law enforcement officer. But she also agreed to grant him leave to re-apply for home detention so he could serve the sentence at a drug rehab facility.

As he left the court, Cossill politely pointed out that he has already served much of that time while awaiting trial and sentencing, so he's likely to be released soon regardless.

The police Eagle helicopter followed Cossill home to his Massey home after a late-night incident at a nearby petrol station in which he was alleged to have gotten into an argument with other patrons during which he first pulled the pistol from his car. He fired the pistol into the air from his car window as he sped off, authorities said.

He returned home and consumed more meth, unaware that police were evacuating his neighbours and calling in the armed offenders squad to surround the home. What resulted was a six-hour standoff that lasted into the next morning.

During that time, he at one point went onto the deck and fired again into the air with the same pistol, Judge Sharp noted during Friday's hearing.

"No police officers or anybody else were actively hit," she said, agreeing with Crown prosecutor Helen Brown and defence lawyer Steve Cullen.

As he came down off the methamphetamine after a number of hours, he began to cooperate with police. During a subsequent search of his home, they also found 32 12-gauge shotgun shells but no other firearms.

The judge also noted that Cossill's mother died when he was 12 and he had violent interactions with his father, who was his caretaker for a short time before the father was sent to prison.

"The problem is Mr Cossill really had no primary caregiver during his formative years," Sharp said, describing his childhood as a "disastrous period of his life" that was made worse when he went into state care.

He is among the many people who have filed an Abuse in State Care claim and has been diagnosed with post-traumatic spectrum disorder, among other lifelong psychological ailments.

"He is clearly suffering from trauma caused by childhood neglect, systemic abuse ..." the judge said. "In other words, Mr Cossill was an accident waiting to happen."

The judge also noted his extensive criminal history along with his membership in the Crips gang, which he has been involved with since his first prison stint. But he's been sentenced to prison extensively in the past and "what good has it ever done"? she asked, answering that it caused an "already damaged man to become a complete recidivist".

She also noted that the person who wrote Cossill's pre-sentence report appeared to be clearly impressed with him despite his very chequered past, noting to the judge that he appeared to be an excellent candidate for rehabilitation.

So Sharp said she'd take a chance on him and try something different.

"I considered you have suffered enough and nobody has given you a chance to address your addictions," she said.

In addition to the using a firearm against a law enforcement officer charge, Cossill was ordered by the judge to serve concurrent sentences for discharging a pistol in a public place, threatening to kill, unlawful possession of a pistol and unlawful possession of ammunition.