A California federal court is to decide for the first time in US history whether amusement park animals are protected by the same constitutional rights as humans.
The issue arises from a lawsuit filed by rights group People for the Ethical Treatment of Animals (PETA) in a San Diego court on behalf of five orcas named Tilikum, Katina, Corky, Kasatka and Ulises.
PETA argues that continuing the whales' "employment" at SeaWorld violates the 13th Amendment to the US Constitution, which prohibits slavery.
The suit, filed in October 2011, asked that the court declare that the orcas are "held in slavery and/or involuntary servitude by defendants in violation of the Thirteenth Amendment to the United States Constitution."
"It's a new frontier in civil rights," said Jeff Kerr, PETA general counsel, who described the hearing as a "historic day."
"Slavery does not depend on the species of the slave any more than it depends on race, gender or ethnicity," Seaworld argued. "Coercion, degradation and subjugation characterize slavery and these orcas have endured all three."
The complaint demands that the court "appoint a legal guardian to effectuate plaintiffs' transfer from defendants' facilities to a suitable habitat in accordance with each plaintiff's individual needs and best interests."
SeaWorld's motion to dismiss argues that, the amendment "only protects people, not animals, from slavery and involuntary servitude."
Seaworld is denying any implications of cruelty to animals and counters that PETA is trying to get attention for itself with its lawsuit.
"While PETA continued to engage in this publicity stunt, SeaWorld San Diego was returning four rescued and rehabilitated sea lions to the wild," SeaWorld said in its response.
"SeaWorld remains the standard for zoological stewardship of marine animals and we reject any challenge to the conditions and quality of care for these remarkable animals."