Attorney Steven Wise is on a crusade to prove that, as a matter of law, chimps are people too.
For that matter, so are dolphins, elephants, gorillas and orcas.
Wise made his argument at the TED Conference that wrapped up in Vancouver, Canada on Friday.
"I had to invent the field of animal juris prudence," Wise told AFP at TED.
"Coming here is implicit affirmation that people are interested in what we have to say."
Wise argued that apes, chimps, elephants and orcas are as entitled to the rights of "persons" under law as are people or corporations.
Legal systems around the world have granted rights of personhood to holy scripts, mosques, companies, and even a river.
"Personhood is not a biological concept, it is a public policy concept," Wise said.
"The legal system decides it; human being is not synonymous with person."
He has devoted decades to the cause, which is now making its way through courts in the US state of New York.
- Seeing animals as slaves -
Wise, president of the Nonhuman Rights Project, is hoping a legal tactic successful in getting a slave legally transformed from property to person in a historic case in Britain will do the same for chimpanzees and other animals.
He will use the writ of habeas corpus, in which judges order prisoners or detainees brought before the court. Such writs, by definition, assign rights of personhood to those targeted.
Members of the project found chimpanzees in abysmal conditions in several parts of the state of New York, then filed for writs of habeas corpus in respective courts to get the animals moved to a refuge.
Reactions from judges have been mixed, with even sympathetic members of the bench averse to breaching the legal wall separating people from animals, according to Wise.
"Even in America, no judge wants to be the first to make this leap of faith," the animal rights champion said.
Wise, author of "Rattling the Cage" and other works defending animal rights, has been waging this legal battle since the early 1980s.
"They truly are slaves," Wise said of chimps, bonobos and other animals proven to have feelings, memories, language, foresight and other traits considered human.
"I realized there was no one looking out for their interests and they were just being exploited."
He recalled being met with hostility and ridicule early in the battle. Rival lawyers would bark when he walked into courtrooms.
After decades of laying groundwork and gathering allies, Wise and his team filed an opening salvo of lawsuits in New York about two years ago.
"We are going state by state, animal by animal and we are going to lose a lot before we start to win," he said.
"I expect to win, and not all that far into the future."
- Tide of history -
Victory would come in the form of a non-human animal being legally recognized as a person for some purpose, no matter how limited.
"Once that wall is pierced, judges will realize that they have to make more nuanced, rational decisions," Wise said of establishing that some animals have a right to be treated better than mere property.
Wise is working with lawyers in Europe, Argentina and other parts of the world.
"I think there is a tide of history and judges need to swim with it and not against it," Wise said.
"Orcas, apes, chimps and elephants should at least have the right to bodily liberty. I am not talking the entire animal kingdom, but lines have to be drawn."
The Nonhuman Rights Project is looking to hit US courts with its next case, on behalf of circus elephants, late this year.
"I think it may change the way people view entities that aren't human," Wise said of his quest.
"They may not have the knee-jerk reaction that we can exploit them."