The most important elephant in the world today was born in Thailand in the 1970s. She was wild and free - but not for long. Less than a year later, the humans arrived. They stole her away from her family and flew her across the Pacific. 

In the USA, she wore a polka-dot dress and gave rides to children. Today, she lives alone in a one acre cage in New York's Bronx Zoo. It is called "Wild Asia". 

But Happy's life may soon take a dramatic turn. In 2018, lawyers filed a claim of unlawful detention, called a habeas corpus petition, on Happy's behalf. They argue that legally, she is a person.

In the new year, a court will decide whether to set HappyHappy was named after Snow White and the Seven Dwarves. She has lived alone since Grumpy, her companion, was attacked by two other elephants and euthanised.  free. If the petition is granted, it will have huge implications. 

At a time of mass extinction and climate change, humanity's relationship with nature has never been more crucial. It is, says one US paper, the "most important animal rights case of the 21st Century". 

There is no doubt: elephants are extraordinary creatures. They live in families, grieve for the dead and can both suffer and understand suffering. 

This is not Happy's first time in the spotlight. In 2005, she became the first elephant to pass the mirror self-identification testHappy repeatedly touched an X painted on her forehead, a place she could not see without a mirror. , a key indicator of self-awareness. 

The philosopher Gary Varner argues that if personhood is defined as conscious awareness of one's past, present and future, then elephants "might be persons - or at least near-persons". 

But personhood in the everyday sense is not the same as personhood as a legal concept. In US law, both corporations and ships are considered persons. 

For the Nonhuman Rights Project (NhRP), who brought Happy's case to the court, the petition is part of a civil rights movement. When the USA became a nation, women, slaves and children did not have personhood. 

The NhRP believe that one day, we will look back at Happy's life with similar horror. If intelligent animals are given some of the same rights as humans, they say, then it could end terrible suffering. 

Others disagree. Granting elephants' personhood would raise questions. Some, like US professor Richard Cupp, fear it could open the floodgates. What would happen to farm animals?   

Cupp even worries that extending personhood could threaten humans. "Society might be tempted not only to look at more intelligent animals as being like humans," he says, "but start to think of less intelligent humans a little more like animals".

Even Joshua Plotnik, the scientist who ran the mirror test, is sceptical. Happy, like all other animals, cannot speak. Why should the NhRP, or any other group, have the right to represent her? 

Still, the landscape is changing. In 2016, an Argentinian court granted great apes legal personhood. The EU acknowledges animals as sentientAble to perceive or feel things.. And last month, a US court recognised hipposThe hippos were once owned by drug boss Pablo Escobar, and are now living free in the Colombian countryside. The Colombian government is seeking to kill or sterilise them. as "interested persons" in a lawsuit. Some say it is only a matter of time before Happy is free. 

Yes, say some. Happy is an intelligent creature who has led a life of suffering far from her jungle home. Public opinion is on her side: nearly half of all Americans believe animals should have the same rights and protections as humans. Granting Happy human rights is the next step on a journey to a more equal world. 

No, say others. Human rights should be reserved for humans. If elephants are granted personhood, it opens the door for chickens and maybe even cockroaches to enjoy the same rights. There are better ways to help Happy, like putting pressure on zoos or changing animal welfare laws.