Orangutans have been granted the status of "non-human persons" with legal rights in a landmark court ruling in Argentina.
The decision clears the way for Sandra, a shy 29-year-old, to be freed from Buenos Aires Zoo after spending her entire life in captivity.
Experts said the verdict could open the floodgates to thousands of similar cases.
The ruling came after animal rights campaigners filed a habeas corpus petition - a document more typically used to challenge the legality of a person's detention or imprisonment - on behalf of the Sumatran orangutan, who was born at a German zoo and was transferred to Buenos Aires two decades ago.
The outcome hinged on whether Sandra should be treated as a "thing" or a "person", with the Association of Officials and Lawyers for Animal Rights (Afada) arguing that she should not be treated as an object because of her intelligence and complex ways of thinking.
The court agreed that Sandra deserved the basic rights of a "non-human person".
Orangutans are part of the family Hominidae - or Great Ape - along with gorillas, chimpanzees and humans. With a name which translates from Malay as "man of the forest", orangutans share about 97pc of their DNA with humans.
"This opens the way not only for other Great Apes, but also for other sentient beings which are unfairly and arbitrarily deprived of their liberty in zoos, circuses, water parks and scientific laboratories," Afada lawyer Paul Buompadre told Argentina's 'La Nacion' newspaper.
Sandra will be transferred to a sanctuary in Brazil unless the zoo appeals within the next 10 days. The zoo was tight-lipped yesterday about its next move.
Sandra's case was the latest in a series that have attempted to give the non-human members of the Great Ape family human status - all of which have failed, until now. (©Daily Telegraph, London)