The Jewish High Holidays begin next week, which means the ultra-Orthodox ritual of kaporos, in which thousands of chickens are ritually slaughtered on city sidewalks, is just around the corner. For years, some Brooklyn-based advocates have demanded an end to the practice, and three years ago they filed a lawsuit accusing the NYPD of turning a blind eye to the illegal butchering, sanitary violations, and animal abuse that they say is endemic to the festival.

A group known as the Alliance to End Chickens as Kaporos is leading the suit, which was previously dismissed by a Manhattan Supreme Court judge, and is now pending before the New York Court of Appeals. On Wednesday, the Animal Legal Defense Fund joined the effort, filling a "friend of the court" brief arguing that the tradition is a clear violation of the state's Agriculture and Markets Law.

"Leaving chickens outdoors without food, water, or protection from the elements, denying injured chickens medical care, and disposing of their bodies in the streets are precisely the types of actions prohibited under New York law," according to the brief.

In years past, members of the alliance say they've witnessed crates full of chickens kept outside without food or water for more than 15 hours. They've documented instances in which the hungry birds have resorted to cannibalism, and watched as police officers refused to intervene. During an unseasonably hot kapparot five years ago, around 2,000 chickens reportedly overheated and died outside a yeshiva in Borough Park.

Practitioners of kaporos say that their legal right to perform the ritual has been upheld multiple times in court. During confrontations with protesters, they point out that far worse abuses happen in slaughterhouses everyday, and accuse activists of singling out the ultra-Orthodox faith.

"My great grandfather did this in Russia. He did nothing wrong," said Moishe Levy, a Chabad follower, during a 2015 event. "All the evil forces in the world don't want the Jews to have their tradition."

But the goal of Wednesday's brief, according to ALDF staff attorney Cristina Stella, is to "highlight the distinction between the religious ritual—a bird swung over the head—and the other parts of the festival that constitute animal abuse."

Tossing half-dead chickens into trash bags, or leaving the animals outside without any food or water, amount to little more than "incidental acts of cruelty," she argues, and have little to do with the ritual of atonement. The custom is practiced in certain Orthodox circles, and is intended to absolve a person of sin in the days leading up to Yom Kippur.

Conceivably, the attorney added, a judge could order the NYPD to issue summonses for specific acts of cruelty, without putting an end to the ritual slaughtering as a whole. "Our feeling is that under the law, the NYPD should be required to take action when there are acts of cruelty taking place," she said.

The NYPD and the NYC Health Department did not respond to requests for comment.

Oral arguments will be heard in the case next month. The kaporos festival is slated to begin on September 15th.