Tommy, a 26-year-old former circus performer, lives on a caravan park in Gloversville in upstate New York, where he spends his days alone, confined to a shed and watching cartoons and nature programmes on television.
His lawyer, Steven Wise, says this is no kind of life for a human. But Tommy is a chimpanzee.
This week, in what is believed to be the first court case of its kind, Wise is arguing that Tommy and other chimps are entitled to "legal personhood".
The Boston lawyer, who is also the president of animal advocacy group the Nonhuman Rights Project, hopes a New York appeals court will rule that Tommy has been unlawfully imprisoned, and should be released to live with other chimps at a sanctuary in Florida.
Keeping Tommy alone in a cage is the same as keeping a human in solitary confinement, says Wise, who has spent much of his career trying to extend human rights and protections to other intelligent animals.
The project says it is "the only organisation working toward actual legal rights for members of species other than our own".
Tommy's lawsuit has been lost in lower courts, but Wise is appealing, citing a legal mechanism that was used on behalf of slaves.
"As a matter of both liberty and equality," he has said, "Tommy should be seen as a person."
In a 65-page legal brief, the project cites several specialists, such as British primate expert Jane Goodall, to argue that chimps are "autonomous, self-determined, self-aware, highly intelligent, and emotionally complex beings who suffer from imprisonment". As such, they fit the legal profile of a "person".
"Person is not a synonym for 'human being'," the brief explains, "but designates an entity with the capacity for legal rights."
Should Tommy win his case, it could lead to broader rights not only for chimps and their fellow primates, but also for other intelligent animals such as elephants, orcas and dolphins.
"The next argument could be that Tommy has the right to bodily integrity, so he couldn't be used in biomedical research," Wise said.
Tommy's owner, Patrick Lavery, has declined to present his case to the appeals court in Albany, but has said the chimp had been on a waiting list for a primate sanctuary for three years, and that his current home was in fact a state-of-the-art US$150,000 enclosure.
Last year, Lavery told the Albany Times Union that Tommy has "got a lot of enrichment. He's got colour TV, cable and a stereo ... He likes being by himself."
In December, Wise will present a similar case to an appeals court in Rochester on behalf of Kiko, a chimp who lives in less-than-salubrious conditions in Niagara Falls.
- Independent