Fiame told RNZ Pacific's Don Wiseman that she could not support three controversial bills that the government is pushing through
Samoa's Fiame Naomi Mata'afa says she quit the government because she believes planned changes to the Land and Titles Court will undermine the rule of law.
Fiame, a long serving MP for the Human Rights Protection Party, was, until last week, deputy prime minister and natural resources minister.
From 2011 to 2016 she was justice minister.
Fiame said she was concerned the autonomy to be granted to the court would amount to a dismantling of the judicial sector, because there would be no oversight of its actions by the Supreme Court.
"They will have a judiciary but with very flimsy provisions around legal issues and processes, and it is the discretionary powers that I am very uncomfortable with.
"You know it's that move away, that slide away from the rule of law into a more loose arrangement," Fiame said.
The government's plans for the Lands and Titles Court have been controversial from the start, largely over worries that it could lead to the alienation of customary land - something the government strongly denied would happen.
A former head of state, Tuiatua Tupua Tamasese Efi, lawyers, and human rights groups, including the UN Human Rights Council, raised concerns.
Some communities mounted petitions seeking a government rethink and a request had also been made to extend the time made available for village consultations.
Fiame said, in her view, the ruling HRPP had become a government that did as it pleased because it had absolute power.
According to the long-standing MP, the party, which has dominated Samoan politics for more than 30 years, has got used to running things as it wants.
"So you know, from a rule of law perspective, and perhaps that's the nature of the controversies over the last few years - it's just that slide away from the rule of law, and people's opportunities to feel confident that they have that safety net available to them."