SAN DIEGO (AP) — An effort to free whales from SeaWorld by claiming they were enslaved made a splash in the news but flopped in court Wednesday.

A federal judge in San Diego dismissed an unprecedented lawsuit seeking to grant constitutional protection against slavery to a group of orcas that perform at SeaWorld parks, saying the 13th amendment applies only to humans.

U.S. District Judge Jeffrey Miller stopped the case from proceeding two days after he became the first judge in U.S. history to listen to arguments in court over the possibility of granting constitutional rights for members of an animal species.

“As ‘slavery’ and ‘involuntary servitude’ are uniquely human activities, as those terms have been historically and contemporaneously applied, there is simply no basis to construe the Thirteenth Amendment as applying to non-humans,” Miller wrote in his ruling.

People for the Ethical Treatment of Animals filed the lawsuit in October and named five whales as plaintiffs. PETA says the wild-captured orcas are enslaved by SeaWorld because they are held in concrete tanks against their will and forced to perform in shows at its parks in San Diego and Orlando, Fla.

SeaWorld called the lawsuit baseless and a waste of the court’s time and money.

Legal experts say it opened an interesting debate about the expansion of animal rights.