"Plaintiffs have not shown they are entitled to this extraordinary remedy," Judge Valerie Caproni said in reading her ruling from the bench.
The judge said she found not "even a whiff" of animus toward religion in statements made by New York Mayor Bill de Blasio in enacting the policy, as argued by the plaintiffs.
The group of 10 teachers lost their bid for a temporary injunction last week, but a three-judge federal appeals court granted the Tuesday hearing.
Caproni also faulted the teachers for waiting to file for an injunction until three days after the mandate took effect.
"I'm baffled by the plaintiffs delay in seeking a preliminary injunction," the judge said, adding such "gamesmanship" does nothing to help the cause.
The teachers had accused the city of being "openly hostile" toward certain religious beliefs.
"Nobody's religious beliefs contrary to the pope's would be valid," plaintiffs' attorney Sujata Gibson said, referencing a September newspaper article: "De Blasio said Thursday that only Christian Scientists and Jehovah's Witnesses have any prayer for a religious exemption."
"I believe that shows animus," Gibson said.
"Why does that show animus?" Judge Caproni asked. "I'm having difficulty getting from that to hostility to religion."
"In nearly every appeal the Department of Education was asking that they be denied on the basis that the pope has been vaccinated," Gibson answered.
An attorney for the city, Laura Manicucci, argued there's no problem with how the mandate is enforced. The plaintiffs were denied because there was something about their claims the arbitrator who evaluates them did not buy.
"Each person's personal religious beliefs would require different kinds of evidence and different kinds of statements and it's up to an arbitrator to determine whether those beliefs apply to vaccination," Manicucci said, adding that more than 20 religions have been represented in exemptions granted so far.
"The mandate is not unconstitutional because it doesn't favor one religion over another and it doesn't give any religion an advantage," Manicucci said.
Toward the end of the hearing the judge appeared exasperated by doubts the plaintiffs expressed about the effectiveness of the vaccines, citing purported experts consulted by the plaintiffs.
"You're losing credibility," Caproni said.
A Law Department spokesperson issued a response from the city.
"Every court that has considered a challenge to the DOE's vaccine mandate has found it to be lawful," the statement read. "What we heard from Judge Caproni today was a resounding confirmation that DOE's vaccine policy is lawful and in the public interest and that there was not a shred of evidence of religious animus by the city in implementing the mandate."
Meanwhile, a federal judge ruled Tuesday that New York must continue to allow health care workers to seek exemptions from a statewide vaccine mandate on religious grounds as a lawsuit challenging the requirement proceeds.
Judge David Hurd in Utica had issued a temporary restraining order a month ago after 17 doctors, nurses and other health professionals claimed in a lawsuit that their rights would be violated with a vaccine mandate that disallowed the exemptions.
Hurd's preliminary injunction Tuesday means New York will continue to be barred from enforcing any requirement that employers deny religious exemptions.
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