The White River First Nation is asking the Yukon Supreme Court to quash a Yukon government decision on an environmental assessment.
It involves Tarsis Resources of Vancouver.
The company is exploring about 70 square kilometers of land in White River traditional territory.
Tarsis applied to do more advanced exploration.
The Yukon Environmental and Socio-economic Assessment Board recommended the plans be denied because harm to the Chisana Caribou herd could not be mitigated.
The Yukon government overturned that recommendation and granted the work.
White River says it was never consulted on the work or the final decision.