A new law being unleashed in California on New Year's Day will give pets' rights some bite in court cases.

The measure provides judges with the power to consider what's in the best interests of the animal in divorce cases, instead of treating them the way they've been treated by courts in the past — as physical property.

"I'm very excited," said David Favre, a professor who teaches animal law at Michigan State University College of Law. "It's important for humans and animals."

The law was sponsored by dog owner and state Assembly member Bill Quirk and signed by dog lover Gov. Jerry Brown (Lucy, a borgie, is the state's first dog and Cali, a bordoodle, is the first deputy dog). The measure empowers judges to consider "the care of the pet animal" and create shared custody agreements.

The law "makes clear that courts must view pet ownership differently than the ownership of a car, for example. By providing clearer direction, courts will award custody on what is best for the animal," Quirk said after the bill was signed.

Yes! Governor Brown has signed my bill to give courts better guidance about how to handle the care of pets during divorce proceedings. Pets are family and should get special consideration. This was the perfect partnership w/@sfspca https://t.co/ozDE7it5kp #AB2274 pic.twitter.com/ieO4C9Chhn — Bill Quirk (@AsmBillQuirk) September 27, 2018

"To treat a pet as property made no sense to me," Quirk told NBC News. "We've actually had judges who said you can sell the dog and split the proceeds."

Legal experts said the law means judges can take into consideration factors like who walks, feeds and plays with the pet when deciding who the animal should live with.

"Before it was an issue of who owns the dog and how you distribute the property," Favre said. "But pets aren't quite the same thing as china and sofas. They're more like children, in that they're living beings who have their own preferences."

And as with children, he said, divorce can be "a trauma for animals as well."

The law doesn't just apply to dogs — it defines "pet" as "any animal that is community property and kept as a household pet."

A 2014 national survey by the American Academy of Matrimonial Lawyers found the vast majority of pet custody fights — 88 percent — had to do with dogs, while cats were the source of strife 5 percent of the time and horses 1 percent. The remaining 6 percent was listed as "other," and included an iguana, python and a 130-pound turtle.

Couples have been fighting over pets in courts for decades, with some judges taking the issue more seriously than others.

In 2000, Stanley and Linda Perkins got into a two-year legal fight in San Diego over their pointer/greyhound mix Gigi. The divorce battle — which wound up costing almost $150,000 — included testimony from an animal behaviorist and a video presentation, a "Day in the Life of Gigi." It showed Gigi sleeping under Linda Perkins' chair and cuddling with her. She was eventually awarded custody — and Stanley Perkins got himself another pointer mix.

But the lack of laws defining pets' rights has led to confusion and animals being treated as regular property.

"Not too many judges are willing to go out on that limb," Favre said.

One who did was Justice Matthew Cooper of the New York state Supreme Court, who greenlighted a pet-custody trial in 2013 over a mini-dachsund named Joey.

"People who love their dogs almost always love them forever," Cooper wrote in his decision. "But with divorce rates at record highs, the same cannot always be said for those who marry."

The case settled before trial and other New York judges at the same level as Cooper have disregarded his ruling in other canine custody clashes. "A court can not predicate a decision on what is best for a dog," one of those judges wrote.

Another judge, Arthur Engoron, said giving dogs extra rights would create a "slippery slope." If "dogs were deemed to have rights, why not cats, raccoons, squirrels, fish, ants, cockroaches? Could you be imprisoned for swatting a fly? Where will it all end?" he wrote in a 2015 decision.

Favre said the California law is a good first step in dealing with inconsistencies in the law, which outside of divorce cases can provide extra legal protection for pets. "There are anti-cruelty laws," he noted. "You can't get arrested for beating up your couch."

The law is the third of its kind in the nation. Alaska was the first to pass a pet "best interest" law in 2017, and Illinois enacted one earlier this year.

"It's an important statute," said David Schaffer, a Chicago matrimonial lawyer. "Many judges saw pets just as a piece of property, a marital asset. Those are the nondog people," said Schaffer, a self-described dog person.

He said the law so far has been a boon, and predicted it would prevent couples from weaponizing their pets in divorce cases. "It can stop a spouse from hurting the other person through the pet" by blocking them from trying to claim the pet as a piece of property, he said.

The Illinois law has an exception for service animals. "If they were yours, they remain yours," Schaffer said.

The California law has a little less teeth than the Alaska and Illinois versions — it says judges "may" consider the pets, but doesn't require them to.

Megan Green, a family law attorney in Los Angeles, said some of her colleagues still have concerns that the measure will further clog the courts.

"A lot of family law practitioners aren't in favor of the new law" because of "how litigious custody cases can be and how overcrowded the courts can be with custody cases," she said.

The new law might lead to situations "where people who have specialties in animal feelings" could be called in to testify, similar to a custody evaluator for children.

Quirk said one of the reasons the law was made optional for judges was to ensure they don't get bogged down in lengthy pet custody disputes. "It prevents that kind of cottage industry from forming," the assemblyman said.

Green said despite the potential headaches, she's all in favor of the new law.

"I have my own pet, Rodney King Stone, and he's treated like a little child," she said of her dog. "I don't believe animals are property — they have feelings."

While the Illinois law has only been in place for just under a year, Chicago lawyer Schaffer said he hasn't seen any pet therapists or animal behaviorists being called in to testify.

"I don't see that here," he said, but "California is an entirely different planet."