To the surprise of a San Diego court, five orca whales are suing Sea World for holding them in slavery.

No wait, that’s not quite right. People for the Ethical Treatment of Animals (PETA) brought the suit on behalf of the five whales. The folks at PETA allege that Sea World’s treatment of the whales violates the 13th amendment’s prohibition against slavery and involuntary servitude.

PETA claims that since the 13th amendment doesn’t forbid human slavery specifically, it could apply to any species: “Slavery is slavery, and it does not depend on the species of the slave any more than it depends on gender, race, or religion.” PETA’s argument is not only absurd constitutional reasoning, but is also a crass exploitation of America’s solemn devotion to the principle of human equality.

The premise of the Declaration and the Constitution is that men are rational beings who cannot be ruled without giving consent. Thomas Jefferson eloquently explained human equality by noting that “the mass of mankind has not been born with saddles on their backs, nor a favored few booted and spurred, ready to ride them legitimately.” In other words, men are not animals and should not be treated like animals.

As for the text of the 13th amendment—“Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction”—the framers did not define slavery because it was universally understood to mean a person holding another human as chattel.

In fact, the language of the amendment was based on the prohibition of slavery in the Northwest Ordinance of 1787, which read: “There shall be neither slavery nor involuntary servitude in the said territory.” By drawing on the language of the Northwest Ordinance—one of the first laws passed by the first Congress—the 13th amendment affirms the self-evident truth that all men are created equal.

By asserting that domesticating animals (incapable of rational deliberation or consent) is morally equivalent to enslaving humans, PETA’s argument makes a mockery of the principle that lies at the heart of America’s devotion to equality and the 13th amendment.