WASHINGTON (OSV News) -- The U.S. Supreme Court heard April 18 arguments in a case that could have broad implications for employees seeking religious accommodations from their employers.

The high court heard oral arguments in Groff v. DeJoy, a case concerning Gerald Groff, an evangelical Christian and former U.S. Postal Service worker, who was denied an accommodation to observe his Sunday sabbath by not taking Sunday shifts.

Federal law prohibits employers from firing employees seeking religious accommodations unless the employer can show that those accommodations cannot be "reasonably" met without "undue hardship." In a 1977 decision in Trans World Airlines v. Hardison, the high court found that the "undue hardship" standard is met even at a minimal cost.

Groff alleged in federal court that USPS failed to provide him with reasonable accommodations for his religious practices after he sought an accommodation not to work Sunday shifts as a faithful Christian.

Groff said he sought employment at the post office since it did not deliver mail on Sundays, however, that practice changed during his employment there, leading him to seek an accommodation. The 3rd U.S. Circuit Court of Appeals ruled in favor of USPS, arguing the post office would face an "undue hardship" by accommodating Groff's request to excuse him from Sunday shifts. But the U.S. Supreme Court agreed earlier this year to take up the case.

During oral arguments, the justices were inquisitive about the facts of the case, with some pondering whether the accommodation sought by Groff was possible for a large employer like USPS, but would present an undue burden to a small business open seven days a week, using the example of a rural grocery store.

The justices also questioned how such an accommodation for some Christians who observe the Sunday Sabbath like Groff does might impact other Christians who still wish to attend church services on Sundays but feel they don't meet the requirements for a similar accommodation.

The Supreme Court's decision has religious liberty implications for Catholics. According to the Catechism of the Catholic Church, "On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord's Day, the performance of the works of mercy, and the appropriate relaxation of mind and body."

The Catholic Church also teaches this "requires a common effort" and both public authorities and employers are obliged to "ensure citizens a time intended for rest and divine worship."

An amicus brief in the case filed on behalf of faith leaders including the U.S. bishops said, "Civil rights are not an issue of good manners only."

"Discriminating because of an employee's religion, including by refusing to reasonably accommodate religious practices without good cause, is unlawful -- and this court should say so," the brief said.

Kelly Shackelford, president, CEO and chief counsel at First Liberty Institute, a group representing Groff, said in a statement, "No American should be forced to choose between their faith and the job they love."

"Our nation has a long history of protecting its employees from being treated differently at work just because of their faith," he said. "We are hopeful the court will restore religious liberty in the workplace."

Groff added in his own statement that "no employee should have to choose between his faith and his career like I did."

"I am grateful to have had my case heard by the U.S. Supreme Court -- an opportunity few others in my situation have ever had," Groff said. "Only God knows the final outcome of my case; I still trust him even if my decision to honor the Lord's Day costs me my career. I hope this case results in a decision that allows others to be able to maintain their convictions without living in fear of losing their jobs because of what they believe."

Others contended religious accommodations should not come at the expense of other employees who would then have to cover those shifts. Rachel Laser, president and CEO of Americans United for Separation of Church and State, argued the case is "a wolf in sheep's clothing," in which some are attempting to accommodate "narrow religious beliefs" at "the cost of everyone else's religious freedom."

"Our civil rights laws rightly require religious accommodations for workers, which is especially important for religious minorities whose rights and customs might not be respected in the workplace," Laser said. "But religious freedom does not mean we can shift the burden of practicing our faith onto other people."

However, Mark Rienzi, president and CEO of Becket, a religious liberty law firm that has filed a friend-of-the-court brief in the case, said in a statement that for almost half a century, "very large employers have been given a get-out-of-jail-free card any time they wanted to kick their religious employees to the curb for observing a holy day or taking time to pray."

"That's all because one bad Supreme Court decision has allowed businesses to exile the faithful to the margins of society," Rienzi said.

Rienzi argued that although the American public "is often skeptical of how Supreme Court decisions affect their real lives," many Americans "have been denied their rights because the Supreme Court got it wrong almost five decades ago."

"In Groff's case, the Court can get the law right once and for all," he said. "Fixing this mistake will help protect millions of hard-working religious Americans from having to choose between their job and their faith."

- - - Kate Scanlon is a national reporter for OSV News covering Washington. Follow her on Twitter @kgscanlon.- - - BRIEF: WASHINGTON (OSV News) -- The U.S. Supreme Court heard arguments in a case April 18 that could have broad implications for employees seeking religious accommodations from their employers. The high court heard oral arguments in Groff v. DeJoy, a case concerning Gerald Groff, an evangelical Christian and former U.S. Postal Service worker, who was denied an accommodation to observe his Sunday Sabbath by not taking Sunday shifts. Federal law prohibits employers from firing employees seeking religious accommodations unless the employer can show those accommodations cannot be "reasonably" met without "undue hardship." In a 1977 decision in Trans World Airlines v. Hardison, the high court found that the "undue hardship" standard is met even at a minimal cost. Groff alleged in federal court that USPS failed to provide him with reasonable accommodations for his religious practices after he sought a religious accommodation not to work Sunday shifts. During oral arguments, the justices were inquisitive about the facts of the case, with some pondering whether Groff's accommodation was possible for a large employer like USPS, but would place an undue burden on a small business open seven days a week, such as a rural grocery store. They also questioned how such an accommodation for some Christians who observe the Sabbath like Groff might impact other Christians who wish to attend church services on Sundays but feel they don't meet the requirements for a similar accommodation.