New York ? With their colorful headgear and repertoire of tricks, they’re top-billed stars of The Greatest Show on Earth.

But away from the arena, the Asian elephants used in the Ringling Bros. and Barnum & Bailey Circus are at the heart of perhaps the most bitter animal-care fight around, one that’s dragged through court for six years already and is inching toward a trial.

It’s a heavyweight bout, pitting America’s biggest circus against some of the most influential animal-welfare groups. Ringling insists that its elephants receive state-of-the-art treatment and it’s determined to keep them in its cast.

Its adversaries – a group including the Humane Society of the United States, the American Society for the Prevention of Cruelty to Animals and the Animal Welfare Institute – argue vehemently that circus life is inherently cruel to the elephants.

They allege that the use of sharpened hooks by trainers, the routine use of chains, the separation of baby elephants from their mothers and other common circus practices add up to an egregious violation of the Endangered Species Act, which covers the Asian elephant and prohibits harm to it. The suit’s goal is a court order halting these practices, which the activists believe would force Ringling to give up elephants altogether.

A seven-month-old Asian elephant named Aree plays with water sprayed from a hose held by Jim Williams, manager for developmental training at the Ringling Bros. and Barnum & Bailey Center for Elephant Conservation in Polk City, Fla.

“It’s impossible to have these animals in captivity the way they are without it leading to abuse – traveling in chains in boxcars up to 50 weeks, performing tricks because of force and intimidation,” said Michelle Thew of the Animal Protection Institute, another plaintiff.

Ringling shows no signs of bowing to pressure, and has become more outspoken in defending itself since the first-of-its-kind suit was filed in 2000. “We train animals through reward, repetition and reinforcement – based on science,” said former zookeeper Bruce Read, Ringling’s vice president for animal stewardship. “Punishment is not used in the circus.”

While the lawsuit protests the use of sharp-ended bullhooks to prod the elephants, Read defends them as “a very accepted tool” developed over many centuries to control the animals humanely. Activists say the implements – which resemble long fire pokers – often inflict scar-causing wounds.

Government regulations permit use of chains. Read said elephants are chained in place at night to keep them from foraging their companions’ food, and during train rides to prevent sudden weight shifts that might derail the freight car.