A devout Christian's choice to put his faith above his job has put him at the center of constitutional fight that is now before the U.S. Supreme Court.

The justices will hear oral arguments Tuesday in a workplace discrimination appeal challenging the high court's 1977 precedent for determining an "undue hardship" on employers when accommodating an employee's religious beliefs and practices.

Mail carrier Gerald Groff sued the U.S. Postal Service after being disciplined for refusing to work on Sundays, when the evangelical Christian said he observes the Sabbath.

Groff says the policy violates his sincere conscience and that he endured a period of harassment and threats from supervisors.

THE POST OFFICE FIRED ME FOR HONORING THE LORD'S DAY. SUPREME COURT MUST MAKE THIS RIGHT

"The response by the Postal Service was brutal. I felt targeted for almost two years," Groff told Fox News Digital. "Rather than respect my religious beliefs, the Postal Service chose to make an example out of me."

The case is the second high-profile appeal over religious liberty to be argued before the Supreme Court this term, an issue where the 6-3 conservative majority has increasingly turned its focus.

Work Matters

Groff was employed as an auxiliary mailman in Lancaster County, Pennsylvania, from 2012 to 2019, a continuous, part-time relief job that often is a first step toward work as a full-time regular carrier.

He believed the job would allow him Sundays off, as his lawyers indicated, "by resting, worshipping with his church family, and serving his family and community."

But a year after he began working, the USPS contracted with e-commerce giant Amazon to deliver their packages, requiring Sunday shifts for deliveries. After discussions with his supervisors, Groff says he was allowed to miss Sunday work, so long as he could personally find a replacement.

Initially, he was able to work out an arrangement with his supervisors to transfer to another branch that did not deliver on Sundays. When that branch also began Sunday deliveries, Groff was permitted to miss his shifts, but it became hard, especially during peak delivery periods, to find someone to cover for him.

First Liberty Institute, a Texas-based Christian conservative legal organization, is representing Groff and claims that the Postal Service subjected him to a letter of warning, two suspensions and other disciplinary measures.

Groff claimed hostile working conditions, which led to hair loss, chronic insomnia, weight gain and anxiety. Both sides disagree over whether his bosses made negative comments about his faith or his observance of it.

IMMIGRATION LAW FACES FIRST AMENDMENT CHALLENGE BROUGHT BEFORE SUPREME COURT

He resigned in January 2019, believing that he would be fired, and later sued. 

"It is unlawful for employers to discriminate against employees on the basis of religion," said Kelly Shackelford, president of First Liberty Institute. "It’s time for the Supreme Court to reconsider a decades-old case that favors corporations and the government over the religious rights of employees."

Several religious groups are supporting Groff, including the American Hindu Coalition, National Jewish Commission on Law and Public Affairs and Council on American-Islamic Relations.

The Justice Department, which will argue the case on behalf of USPS, wrote in a filing, "Despite the Holtwood Postmaster’s 'undisputed good-faith efforts' to find volunteers to cover petitioner’s Sunday shifts each time he was scheduled to work, petitioner ultimately missed at least 24 shifts that were not filled with shift swaps," during a 14-month period. "In response, USPS took disciplinary measures, including imposing 'paper suspensions' that did not result in a loss of work or pay."

Postal executives said Groff's absences created a "tense atmosphere" among the other small group of "Rural Carrier Associates" (RCAs), who began to complain about having to regularly fill in for him on Sundays.

The Postal Service said the nature of RCAs at the four-person post office was to work on an as-needed basis, with flexible hours that included weekend and holiday shifts.

"A union member working at the hub submitted a grievance in 2017, alleging that he had been forced to work on Sundays during non-peak season to cover for [Groff], in contravention of" an agreement between USPS and the labor union representing RCAs, according to the federal government. Disciplinary measures against Groff then proceeded.

Several other labor unions, as well as 11 states, have filed briefs supporting the Postal Service.

SUPREME COURT TAKES UP RELIGIOUS FREEDOM CASE INVOLVING POSTAL WORKER WHO REFUSED TO WORK ON SUNDAY

Other groups opposed to Groff's lawsuit point to a "statement of facts" filed with the high court on behalf of both parties, in which Groff admitted he "did not spend the whole day in church on Sundays. The plaintiff watched NASCAR on Sundays."

Key Precedent

A federal appeals court in Philadelphia ruled for the Postal Service, concluding Groff's absences "placed a great strain on the Holtwood Post Office personnel and even resulted in the Postmaster delivering mail" and "also had an impact on operations and morale... and made timely [mail] delivery more difficult."

Title VII of the Civil Rights Act of 1964 makes it unlawful "to discriminate against any individual with respect to his compensation, terms, conditions, or privileges of employment, because of such individual’s ... religion." That includes "all aspects of religious observance and practice, as well as belief, unless an employer demonstrates that he is unable to reasonably accommodate to an employee’s … religious observance or practice without undue hardship on the conduct of the employer’s business."

In 1977, the Supreme Court ruled that federal law requires employers to make good-faith efforts to accommodate an employee's faith, or show that in doing so, they would "bear more than a de minimis cost." 

In that ruling, the court said TWA Airlines could dismiss an airport maintenance worker's refusal to work on the Sabbath, under Equal Employment Opportunity Commission (EEOC) guidelines. That 7-2 opinion said the company and the labor union had taken "reasonable" measures to work out an accommodation with the worker, Larry Hardison, but said that TWA should not have to operate shorthanded or regularly pay premium wages to secure replacement workers.

Several conservative justices in recent years have questioned that precedent.

APPEALS COURT RULES AGAINST CHRISTIAN MAIL CARRIER WHO SUED USPS OVER SUNDAY SHIFTS

Justice Neil Gorsuch, in 2021, had urged his colleagues to revisit the issue, saying the 46-year-old ruling "dramatically revised — really, undid— Title VII’s undue hardship test … [and that] the company had no obligation to provide [the employee] his requested accommodation because doing so would have cost the company something (anything) more than a trivial amount."

"There is no barrier to our review and no one else to blame," said Gorsuch, who was supported at the time by Justice Samuel Alito. "The only mistake here is of the Court’s own making — and it is past time for the Court to correct it."

The high court will now get its chance.

Religion and the Courts

It is a bedrock principle of the Constitution's First Amendment: "Congress shall make no law respecting an establishment of religion or prohibiting the free exercise thereof." Tension between those government and individual principles has been especially acute in the past six decades, as judges have been asked to ensure, when protecting one side, that they do not go too far in violating the other. The Supreme Court has interpreted such laws be enforced in a manner that is neutral toward religion.

That has led to a mixed record of sorts on a range of such disputes, and the justices often employ a default case-by-case determination. The high court has allowed some religious-themed displays on public property, while banning others. So, too, when it comes to legislative and school prayers; and taxpayer funds to religious organizations, even for secular purposes.

The high court, in 1971, established its three-prong "Lemon" test, named for one of the parties in the case. It embedded legal standards in the relationship between church and state.

But the approach has had its critics. The late Justice Antonin Scalia, in 1993, tweaked his colleagues for their "wavering" application of precedent.

"Like some ghoul in a late-night horror movie that repeatedly sits up in its grave and shuffles abroad, after being repeatedly killed and buried, Lemon stalks our Establishment Clause jurisprudence once again," he wrote. "It is there to scare us (and our audience) when we wish it to do so, but we can command it to return to the tomb at will."

Justice Clarence Thomas was more succinct in 2011, saying the court's jurisprudence on church-state matters was "anyone's guess."

Evolving Law

This is the second high-profile religious liberty dispute the high court is confronting this term.

The justices in December held oral arguments in a case brought by a Colorado web-designer, who seeks to expand her portfolio to include custom wedding celebration websites.

I’M A CHRISTIAN AND I'M SUING MY STATE BECAUSE IT REFUSED TO LET ME ADOPT CHILDREN

But in keeping with her religious tenets, she does not want to publish any such sites for gay or lesbian couples. Smith pre-emptively claims that she would be prevented by the state's anti-discrimination law from posting a disclaimer on her own homepage about those views.

The court's conservative majority offered qualified support for Lorie Smith during arguments, and a ruling is due in the next few weeks.

By wading again into a politically charged debate, the justices will have to confront recent decisions on religious liberty.

In 2019, a large concrete veterans memorial in the shape of a Christian cross on government property was allowed to stand. And this past June, a public high-school football coach who had prayed on the field after games in the presence of students was allowed to get his job back.

As Gorsuch wrote in the coach's case, "The Constitution and the best of our traditions counsel mutual respect and tolerance, not censorship and suppression, for religious and nonreligious views alike."

The current dispute over Gerald Groff's appeal is expected to draw a similar ideological divide, pitting individual constitutional rights against workplace accommodations.

"I hope the Supreme Court reaffirms our nation’s commitment to providing equal opportunity and fair treatment in the workplace," Groff told Fox News Digital. "No employee should be forced to make the same decision the Postal Service forced upon me: faith or job."

The Postal Service is an independent government agency that does not use taxpayer money for its operations.

The case is Groff v. DeJoy (22-174). A ruling is due by late June.