Five killer whales are 'suing' SeaWorld, after Peta (People for the Ethical Treatment of Animals) filed a lawsuit on the orcas' behalf.
The animal rights group are arguing that the orcas have a constitutional right to freedom in the same way that humans do and the killer whales are being treated as slaves.
They are asking a judge to free the 'enslaved' orcas from San Diego and Orlando SeaWorld, where they live in tanks and perform complex routines for the waiting crowds.
The five orcas were captured in the wild. Peta has named the killer whales as Tilikum and Katina, at SeaWorld Orlando and Kasatka, Corky, and Ulises, at SeaWorld San Diego.
Tilikum is perhaps the most well known of the orca plantiffs. In February 2010, he drowned his trainer before an audience when of the tricks went wrong.
Since then no humans have been allowed in tanks with the killer whales at Florida Sea World. Tilikum has also been linked to two other deaths, after marine park workers drowned in tanks that Tilikum has inhabited.
Orca Tilikum was allowed back to perform, despite having a reputation as a dangerous animal.
Peta's argument to free the killer whales rests on the basis of the 13th Amendment to the US constitution, which bans "slavery or involuntary servitude." However SeaWorld legal team has slammed the lawsuit saying it was a "waste of time and resources."
Despite that they presented their case at a court in San Diego, saying that the killer whales were not "enslaved" in a legal sense because animals were not included in the constitutional amendment.
"Neither orcas nor any other animal were included in the 'We the people'... when the Constitution was adopted." Theodore Shaw, SeaWorld's lawyer told the court. Shaw referred 'We the people' as the constitution begins with "we the people of the United States."
SeaWorld have also asked the judge to dismiss the case, saying that Peta are only asking for Sea World to release the whales as a publicity stunt. They have said that if the orcas are released on grounds of slavery, then similar rationale could be applied to guide dogs and police sniffer dogs as well as zoos.
Killer whales perform at SeaWorld
Peta argued that SeaWorld was being hysterical in saying this, but the district attorney overseeing the case, Judge Jeffrey Miller, appeared to dismiss Peta's claims, The Los Angeles Times reported.
"Call me hysterical, but that's one of the first places I went in my thinking about this case," Miller said.
It seems unlikely that the marine park will actually be compelled to release the orcas. But animal rights campaigners are happy that the case made it to court at all, with a Peta spokesperson calling it an "historic day."
An orca performs at another SeaWorld park in America.