Anti-whaling group Sea Shepherd will have to stay at least 500m away from Japanese whaling ships in the Southern Ocean, following a ruling in a US court.
The injunction, ordered by the US Court of Appeal earlier this week, bans Sea Shepherd and its captain, conservationist Paul Watson, from physically attacking vessels in the whaling fleet.
In addition, they are banned from "navigating in a manner that is likely to endanger the safe navigation of any such vessel" and must stay at least 500m away.
In a statement on its website, Sea Shepherd said it's committed to achieving a zero-kill quota on whales.
"We expect that the Japanese whaling fleet was waiting for this ruling before departing from Japan.
"They will find when they arrive that we will still be there guarding the Southern Ocean whale sanctuary with our ships and our lives."
Sea Shepherd ships and Japanese vessels have collided in the past, although both sides have blamed each other for the strikes.
Japan uses a loophole in International Whaling Commission rules that allows whales to be killed for scientific research.