Barngarla Traditional Owners take their fight against a planned radioactive waste facility near Kimba on the Eyre Peninsula to the Federal Court on Monday, 6 March.
Australian Conservation Foundation's nuclear analyst Dave Sweeney said the Foundation "respects the Barngarla people's concerns and efforts" and stands "alongside them in this effort".
"It is deeply disappointing the federal Labor government is continuing to advance a deeply deficient waste plan inherited from the former Coalition era," he said.
"The plan is based on false assumptions and would deliver sub-optimal outcomes."
The Barngarla challenge, set to be heard throughout the week, seeks to overturn former Resources Minister Keith Pitt's declaration of the Kimba site.
Recent Senate Estimates revealed the federal government is outspending the Barngarla on a four-to-one ratio, the ACF noted.
"This is a David and Goliath battle," Mr Sweeney said.
"Unlike the Barngarla, the federal government has access to significant resources and considerable power. The government should be using these to advance real solutions, not radioactive pollution."
Former Minister Pitt attempted to preclude Barngarla from seeking legal redress but was thwarted by political opposition from federal Labor as well as the Greens and others on the crossbench.
"It is good that Barngarla have a day or five in Court this week, but they should not have to go down this route," Mr Sweeney said.
"It would be better if the federal government put the brakes on the site selection process and started genuine and respectful engagement that listens to and reflects the legitimate cultural, environmental and economic concerns of First Nations people.
"It is time for Canberra to change course and adopt responsible radioactive waste management rather than division and dumping."
South Australian Premier Peter Malinauskas has backed the Barngarla Native Title holders' right to veto the project and in October the South Australian Labor state convention found that the waste plan "undermines efforts toward reconciliation".
Last November a spokesperson for federal Resources Minister Madeleine King told National Indigenous Times that the facility will help "fulfil Australia's obligation to responsibly manage its own radioactive waste, most of which comes from making nuclear medicine".
It is understood that national and state environment, Indigenous, public health and trade union supporters will gather at the Federal Court, Angas St, Adelaide, from this morning to show support to the Barngarla delegation before they enter the Court.