The Sea Shepherd takes battle with Japanese whalers to the U.S. Supreme Court

The Sea Shepherd conservation group asked the US Supreme Court on Monday to lift an order forcing it to steer clear of Japan's whalers, who are seeking legal reprisals over harassment at sea.

Since 2002, Sea Shepherd has annually disrupted Japan's contested hunt in the Southern Ocean but a US court issued an injunction on December 17 for the activists to stay at least 500 yards (meters) away from the whaling vessels.

Environmental lawyer Robert F. Kennedy Jr., the son and namesake of the slain political icon, urged the United States to show support for the Sea Shepherd Conservation Society and its fugitive founder Paul Watson.

"It's a mission that only they are capable of accomplishing and that is absolutely vital to the enforcement of international agreements on the high seas which otherwise go unenforced," Kennedy told reporters.

The International Whaling Commission has designated a whale sanctuary in the Southern Ocean. Japan kills whales in the area through a loophole in a 1986 moratorium on commercial whaling that allows lethal research.

Kennedy called Japan's government-supported Institute of Cetacean Research, which runs the whaling program and sued Sea Shepherd, "a pirate organization masquerading as a scientific research group."

In a filing to the Supreme Court on Friday, Sea Shepherd and Watson said that the lower court "acted rashly" and voiced concern over the order's "extraordinarily long reach" to areas outside US jurisdiction.

The document said that the injunction marked "a potentially existential threat" to Sea Shepherd as more than 80 percent of its funding comes from donations, which "may slow to a trickle" without the anti-whaling campaign.

The US Court of Appeals for the Ninth Circuit cited safety concerns when it issued the injunction, effective until a decision on the case.

The Institute of Cetacean Research hit back and was believed to have asked the judge to find Sea Shepherd in contempt of court -- which would potentially lead to punishment.

Sea Shepherd released a letter from a lawyer representing the institute, which complained that MV Brigitte Bardot, a former ocean racer named after the French actress and animal rights activist, violated the 500-yard injunction on January 29.

The letter warned of legal action unless Sea Shepherd ordered the Brigitte Bardot to comply with the injunction or returned it to port.

The Oregon-based group contended that it was observing the injunction, saying that the Brigitte Bardot sails under an Australian flag and is operated by Sea Shepherd's Australian sister organization.

Japan's institute is "just like a bully who is finally challenged and runs to his mommy," said Scott West, the director of intelligence and investigation for US Sea Shepherd.

Sea Shepherd boasted that it has prevented Japan from killing whales this season. Japan, which makes no secret that meat from whaling ends up on dinner plates, accuses Western nations of disrespecting its cultural traditions.

Gavin Carter, a US-based spokesman for the Institute of Cetacean Research, called Sea Shepherd's Supreme Court filing an "unusual approach."

Watson, a dual US and Canadian citizen, has kept his whereabouts unknown since July, when he jumped bail in Germany, where he was arrested on charges from Costa Rica related to a confrontation over shark finning.