A judge in the United States has refused a request to prevent Sea Shepherd from disrupting Japanese whalers.
Several Japanese whaling groups, including the Institute of Cetacean Research, were seeking a court order to prevent Sea Shepherd from attacking their ships in the Southern Ocean.
The group said crew members were put in danger by the actions of the organisation, which it described as essentially self-proclaimed pirates.
The judge in the state of Washington rejected the request. A full judgement was to be issued later.
The Japanese whaling fleet left the port of Shimonoseki on 6 December on its annual hunt.
The ABC reports that Sea Shepherd members have been involved in several clashes with Japanese whalers since then.