"I feel, in hindsight, I should have at least voiced my concern about the way in which the operation was carried out."
Mr Ririnui told APNZ the Maori members of Labour had stood their ground to have some way of improving the Bill.
"There was a price to pay for the position we took, some of us weren't happy about it."
Mounting pressure from constituents and family to oppose the legislation made the process all the more difficult.
"I would go to a community hui at my marae in Tauranga and no-one would talk to me, not even look at me," he said.
"Having my children abused by their own cousins about their father selling Maori rights down the drain, being a sell-out and a kupapa."
Mr Ririnui said there were scars that had not healed from that time.
"The lack of trust, the lack of support - I still carry that."
Mr Ririnui first arrived in Parliament as the MP for the Maori electorate of Waiariki, and counts his private member's bill, the Bay of Plenty Maori Empowering Bill, as his greatest achievement.
"What that meant was the Bay of Plenty Regional Council was the only regional council in the country with Maori wards," he said.
"That for me was a major achievement, it was a major challenge, with considerable resistance from other political parties."
Among his other regrets, Mr Ririnui noted being caught using his ministerial credit card to buy items that broke the rules, such as golf clubs and a bike, for which he was demoted to the party's backbench.
In Parliament today, Mr Ririnui delivered his farewell with an open shirt and no tie.
"The reason I'm not wearing a tie is I intend to live a much more relaxed lifestyle post-Parliament, and enjoy every day as it comes."