(CNN) The Supreme Court on Friday denied a request to block a Maine rule that requires certain health care employees to be fully vaccinated against Covid-19.
A group of unvaccinated workers argued that the vaccine mandate violated their religious liberty rights.
The court's right wing -- Justice Neil Gorsuch, Clarence Thomas and Samuel Alito -- dissented and would have halted the mandate while the appeals process plays out.
The court's move is the latest instance in which the justices have turned away a request to halt a vaccine mandate and it comes as states are grappling with the delta variant.
Writing for his two conservative colleagues, Gorsuch pointed to the fact that "unlike comparable rules in most states," Maine's rule "contains no exemption for those whose sincerely held religious beliefs preclude them from accepting the vaccination" but it does have a medical exemption.
Gorsuch said that Maine's decision to deny a religious exemption "borders on the irrational" and that the state had failed to present any evidence that granting the religious exemption "would threaten its stated public health interests any more than its medical exemption already does." Health care workers behind the suit, "who have served on the front line of a pandemic for the last 18 months, are now being fired and their practices shuttered" all for "adhering to their constitutionally protected religious beliefs."
He added: "Their plight is worthy of our attention."
Justices Amy Coney Barrett and Brett Kavanaugh voted with the majority to allow the mandate. In a brief statement, Barrett said that she decided against voting to grant such "extraordinary relief" in part because the case arose on the court's emergency docket and the justices did not have the benefit of a full briefing and oral arguments.
Over the last few months, the justices had declined invitations to strike down vaccine mandates at Indiana University and New York City schools, but the Maine dispute targeted religious liberty concerns.
The Maine vaccine mandate -- that requires designated health care facilities, dental health providers and emergency services organizations to require that their employees to get the vaccine -- went into force on Friday. The workers bringing the suit argued that it violates the Constitution and Title VII, federal civil rights law that bars employment discrimination based on religion. While Maine offers a limited exemption for some medical situations, it does not consider requests for religious objections.
"Maine has plainly singled out religious employees who decline vaccination for religious reasons for especially harsh treatment," Mathew Staver, a lawyer for Liberty Counsel, representing the workers, wrote in court papers. At the same time, Staver said the state has been "favoring and accommodating employees declining vaccination for secular, medical reasons."
Staver said the workers object to the vaccines because of the way that they were either "developed, researched, tested, produced or otherwise developmentally associated with fetal cell lines that originated in elective abortions."
It is an argument that has been made before. The Catholic Church and the Congregation for the Doctrine of the Faith, the church's highest doctrinal authority, have wrestled with the moral permissibility of receiving Covid-19 vaccines because of their distant relation to fetal cell lines developed from abortions in the 1970s and 1980s.
The AstraZeneca and Johnson & Johnson vaccines were developed using aborted cell lines, though the final product does not contain fetal cells. The Pfizer and Moderna vaccines were not manufactured from fetal cell lines and the final product does not contain fetal cells, although their testing used these cell lines.
The Vatican's Congregation for the Doctrine of the Faith said in a note approved by Pope Francis that receiving the shot was morally permitted. "It is morally acceptable to receive Covid-19 vaccines that have used cell lines from aborted fetuses in their research and production process," the note said.
But the health care workers, including one health care provider who operates his own private practice in the state, still objected. The provider doesn't want to receive the vaccine and he wants to honor the beliefs of his employees who also object. When the mandate goes into force, he says he will face the revocation of his license and the shuttering of his practice.
Maine Attorney General Aaron Frey urged the justices to let the mandate stand, saying that the pandemic has "gripped" the state with 100,937 total confirmed cases and 1,122 deaths as of October 2021. He said the mandate was necessary to "prevent the spread of Covid" in high-risk places and that it did not target religious practice.
A medical exemption is necessary, he said, "because there are certain circumstances when vaccination may cause adverse health consequences, thereby actually harming that individual."
This story has been updated with additional details Friday.