The environmental group Sea Shepherd filed a lawsuit on Friday in a bid to block New Zealand seafood exports to the United States.
The legal action was done to protect the Māui dolphin from extinction, the group said.
The lawsuit was filed against the US Department of Commerce, the Department of Homeland Security, NOAA Fisheries and the US Treasury Department.
"These agencies have failed to take legally mandated action to ban imports from the New Zealand fisheries that are driving the Māui dolphin to extinction," Sea Shepherd said.
According to the Marine Mammal Protection Act (MMPA) US agencies are required to prohibit imports from foreign fisheries that fail to prevent bycatch of marine mammals in line with US standards, Sea Shepherd said.
"There is no question that New Zealand fails to meet such standards in the case of the Māui dolphin."
It is estimated there are only around 60 of the endangered dolphins left in the world. Sea Shepherd says at least three dolphins each year are killed in bycatch.
A threat management plan for Māui and Hector's dolphins is currently being considered by the Government here after a consultation period last year.
Jeremy Helson, chief executive of Seafood New Zealand, told Newshub he believes the lawsuit filed by Sea Shepherd is a "tactical move to both accelerate that process and panic the New Zealand Government to make changes under a pressured situation".
He said there had been no Māui dolphin deaths reported due to fishing since 2002.
According to a risk assessment prepared for the threat management plan review, said Helson, "fishers might currently capture one Māui dolphin every nine years, below the level of capture needed to ensure the long-term viability of the Māui dolphin population".
"By way of contrast, the assessment estimated that toxoplasmosis, a cat-borne disease, may be killing nearly two Māui dolphins each year and accordingly poses the greatest threat to Māui dolphins."
Fisheries New Zealand could not comment on the issue as it was before the courts in the United States, a spokesperson said.
