Can parents challenge a ban on religious exemptions for school vaccinations? The Connecticut Supreme Court took up that emotionally charged debate on Thursday.

State lawmakers ended religious exemptions in 2021, leading some parents to protest.

"I don't want the government deciding what I inject in my body," Dave Joseph, of Hartford, told News 12 Connecticut in July 2021.

All new students must now be vaccinated unless they have a medical excuse. However, unvaccinated students who were already enrolled when the law took effect can stay in school.

Keira Spillane, of Orange, is one of the two parents challenging the law. Her son is unvaccinated and can't attend school.

"I try to explain to my kid why he can't go to school with his sister," Spillane said in July 2022. "She gets on the bus, and he can't get on the bus."

Spillane's case moved to the state's highest court on Thursday.

Lawyers for the state urged judges to dismiss her lawsuit. Assistant Attorney General Darren Cunningham argued that the state enjoys "sovereign immunity" for most laws. He warned of an avalanche of frivolous lawsuits if Spillane's case is allowed to move forward.

"When you're talking about school vaccination laws and you're talking about a lot of – potentially a lot of – students affected and a vocal community, you could really have the floodgates of litigation opened," Cunningham said.

But Spillane's attorney said the state's immunity is waived, because the new vaccination law infringes on parents' religious freedom.

"We are arguing that the state's removal of religious exemptions violates both the state and federal constitutions, and a state law called the Religious Freedom Restoration Act," said attorney Lindy Urso. "The state's position is basically that there is no recourse ever if the Connecticut Legislature violates an individual's constitutional rights. We think that is wrong."

Even if the state Supreme Court allows this lawsuit to go forward, it faces an uphill battle. The religious exemption law has already survived other challenges in federal court.