Where gender was recorded, 92 per cent of those who received first warnings so far were male and 59 per cent were under 30.
Where ethnicity was recorded, half (49.6 per cent) were Maori - much more than the Maori share of New Zealand's population (15.3 per cent), but in line with their share of existing prisoners (50.4 per cent).
Another 14.3 per cent were Pacific people, higher than both the Pacific share of the population (7.8 per cent) and their share of existing prisoners (11.2 per cent).
Only 31.8 per cent were European, less than half their share of the population (75 per cent) and slightly below their share of existing prisoners (34.4 per cent).
Dr Oleson said the lopsided effect of the three strikes law was paralleled in California, which passed one of the world's first such laws in 1994, where 70 per cent of those affected were either black or Hispanic.
Other speakers at the conference said the dominance of Maori in New Zealand crime statistics stemmed from the way the British takeover of the country in 1840 destroyed the close relationships that determined social behaviour before colonisation.
Victoria University doctoral student Terikirangi Mihaere said council restrictions on developing Maori land drove most Maori out of rural areas and into the cities between 1945 and 1965, creating a "lost generation" of young urban-born Maori who reached adulthood around 1980 without the language, culture or social ties that their parents had been born into.
"I am one of that generation. I grew up without the language, separated from our marae," he said.
"We didn't understand what it meant to be a Maori, but struggled to find a place in the Pakeha world. We didn't belong in either world."
He said it was no coincidence that Maori leapt to 50 per cent of the prison population by 1980, and stayed there.
Maori make up an even higher proportion of female prisoners - 57 per cent in June last year, and 71 per cent of female prisoners under age 25.
Auckland University sociologist Dr Tracey McIntosh, who is doing research in the Auckland women's prison, said the Wiri remand unit was "like a Maori single-sex boarding school - it's young and it's Maori".
She said most of the girls' parents were in gangs.
"They are born into it. Their parents were in gangs, often their grandparents were in gangs.
"They have very, very constrained life opportunities. We need a lot more work in this area.
"Given the fact that women are likely to become mothers, even though only 8 per cent of the prison population is female, we need to invest in these young women."
Three strikes
* First warnings, 2010-12
* Maori 687
* European 440
* Pacific 198
* Asian/Other 59
* Unknown 109
Total 1493
