Vailagilala, now aged 28, arrived in New Zealand in 2009 through adoption by his aunt.
Among family he will leave behind in New Zealand when he is released from his 13-year sentence for murder in 2026 and deported, is his twin brother.
The immigration and protection tribunal heard from the twin about their special bond, saying he felt as though a part of him was missing since his brother was jailed in 2013.
A psychologist explained identical twins were "as close as two people can be [...] They often make the comment that being an identical twin 'is like having a built-in best friend for life'. [Vailagilala and his twin] have spent their entire life together up until the date of his incarceration. It is obvious that their entire lives together has resulted in them being both psychologically and emotionally very close."
By 2026, on the appellant's earliest release from prison, he will have spent nearly 17 years in New Zealand.
The tribunal ruled that his close family links here amounted to exceptional circumstances of a humanitarian nature but said that had to be balanced against the gravity of his crime.
After his trial, the sentencing judge said it was clear he had started the 2011 attack by tackling the man to the ground before his co-defendants joined in. "It was a nasty, murderous assault and it was three on to one. It continued through and beyond a stage where [the victim] would have been totally unable to defend himself having been overwhelmed by serious force used against him."
The tribunal ruled it was not unduly harsh or unfair for him to be deported.
"In the appellant's case, murder is a very serious crime and his offending was a serious example of its type, which he committed within two years of his arrival in New Zealand."