A US federal judge in Seattle has declined to immediately restrain the activities of an anti-whaling group.
Judge Richard Jones said he would issue a written ruling later, but that he was inclined to deny a request for a preliminary injunction made by Japanese whalers against the Sea Shepherd Conservation Society.
The whalers - the Institute for Cetacean Research - said the Sea Shepherd group had attacked and rammed their ships off Antarctica during the whaling season, and asked the judge to order them to stop. Some of the clashes have been shown on the Whale Wars reality TV show.
Sea Shepherd activists use stink bombs and other nonlethal means to interfere with the whalers. The group argues that its activities are supported by international law, that the court does not have jurisdiction in the Southern Ocean, and that it is the whalers who have rammed its vessels.
In a federal lawsuit filed in Seattle on December 8, the institute argued that the whalers are "entitled to be free from attack by what are essentially self-proclaimed pirates with a base in the state of Washington".
Japan's whaling fleet kills up to 1000 whales a year, an allowed exception under a ruling by the International Whaling Commission.
Japan is permitted to hunt the animals as long as they are caught for research and not commercial purposes. Whale meat not used for study is sold as food in Japan, which critics say is the real reason for the hunts.
Activists launched or threw glass bottles containing paint or butyric acid in one attack last year, the captain of a whaling vessel said in an affidavit translated from Japanese.
"A crew member could be blinded in such an attack," said Tomoyuki Ogawa, captain of the Nisshin Maru. "These attacks also cause fear in the crew, thus interfering with the prompt and accurate carrying out of orders."
Sea Shepherd president Paul Watson said in documents that his activists have never injured any whalers. He accused the whalers of attacking activists with concussion grenades, long-range acoustical devices, bamboo spears, heavy nuts and bolts, water cannon and prop foulers.
Each hunting season runs from about December through to February.
Sea Shepherd has sent boats to the waters off Antarctica for the past several years in an attempt to thwart the hunt. The two sides have occasionally had violent clashes, including a skirmish in which a Sea Shepherd boat was sunk after its bow was sheared off in a collision with a whaling ship.