SAN FRANCISCO — Their supporters call them heroes. The Japanese government calls them terrorists.

Late Monday, the United States’ largest federal court labeled them pirates.

In doing so, the 9th U.S. Circuit Court of Appeals castigated Paul Watson and members of the Friday Harbor-based Sea Shepherd Conservation Society he founded for the tactics used in their relentless campaign to disrupt the annual whale hunt off the dangerous waters of Antarctica.

“You don’t need a peg leg or an eye patch,” Chief Judge Alex Kozinski wrote for the unanimous three-judge panel. “When you ram ships; hurl glass containers of acid; drag metal-reinforced ropes in the water to damage propellers and rudders; launch smoke bombs and flares with hooks; and point high-powered lasers at other ships, you are, without a doubt, a pirate, no matter how high-minded you believe your purpose to be.”

Unlimited Digital Access. $1 for 4 weeks.

The same court in December ordered the organization to keep its ships at least 500 yards from Japanese whalers. The whalers have since accused the protesters of violating that order at least twice this month.

The ruling overturned a Seattle trial judge’s decision siding with the protesters and tossing out a lawsuit filed by a group of Japanese whalers seeking a court-ordered halt to the aggressive tactics, many of which were broadcast on the Animal Planet reality television show “Whale Wars.”

U.S. District Judge Richard Jones had sided with Sea Shepherd on several grounds in tossing out the whalers’ piracy accusations and refusing to prohibit the conservation group’s protests. He determined the protesters’ tactics were nonviolent because they targeted equipment and ships rather than people.

The judge also said the whalers were violating an Australian court order banning the hunt and so were precluded from pursuing their lawsuit in the United States.

The appeals court called Jones’ ruling “off base” and took the rare step of ordering the case transferred to another Seattle judge to comply with its ruling Monday. The appeals court said Jones had misinterpreted the Australian ruling, which didn’t address the protesters’ actions.

“The district judge’s numerous, serious and obvious errors identified in our opinion raise doubts as to whether he will be perceived as impartial in presiding over this high-profile case,” Kozinski wrote.

Charles Moure, an attorney representing Sea Shepherd, said the pirate label came as a surprise.

“My clients are not pirates who do this for private gain,” Moure said. “Their actions are nonviolent, so we definitely dispute that opinion.”

Late-afternoon calls to the Sea Shepherd Conservation Society were not returned Tuesday.

But Puget Sound whale conservationist Fred Felleman said he was happy to hear the court opinion today. For years, Felleman said, he’s feared that the tactics used by Sea Shepherd members would result in confrontations so violent that someone might be killed.

That fear began when Watson led protests in the late ’90s against a Makah tribe treaty allowing limited whaling. The protests were so heated and invasive, Felleman said, that it further galvanized the tribe to pursue whaling rights.

“It makes for great television, but also for poor political resolution,” Felleman said. “They are all about emphasizing themselves, rather than the cause.”

Moure said he would ask an 11-judge panel of the 9th Circuit to reconsider the injunction prohibiting Sea Shepherd members from practicing aggressive protest techniques, and reconsider Judge Jones’ removal from the case.

Seattle Times reporter Alexa Vaughn contributed to this report.