J. Scott Applewhite, AP
People visit the Supreme Court in Washington, Monday, June 26, 2017, as justices issued their final rulings for the term, in Washington. The high court is letting a limited version of the Trump administration ban on travel from six mostly Muslim countries take effect, a victory for President Donald Trump in the biggest legal controversy of his young presidency. (AP Photo/J. Scott Applewhite)

The Supreme Court is diving back into the same-sex marriage debate, announcing Monday that it would hear a case that asks whether small business owners can refuse to serve same-sex couples, particularly when they provide expressive services such as cake decorating.

Masterpiece Cakeshop, Ltd. v. Colorado Civil Rights Commission pits a baker represented by the Alliance Defending Freedom, a conservative law firm, against two, married gay men represented by the American Civil Liberties Union. The Supreme Court's ruling should help resolve tension that's been brewing since the high court legalized same-sex marriage two years ago.

The high-profile case originated in 2012, when David Mullins and Charlie Craig stopped in to Masterpiece Cakeshop in Denver to ask about a cake for their wedding reception. When the store's owner, Jack Phillips, realized that they were the couple being wed, he said his religious beliefs wouldn't allow him to take part in the event.

The couple's social media post about the interaction went viral, and the ACLU helped them take legal action.

"Craig and Mullins filed a civil rights complaint and won, first before an administrative court judge, then before the state Civil Rights Commission, and finally before the Colorado Court of Appeals," USA Today reported. It's been nearly a year since Phillips filed his appeal to the Supreme Court, so some had predicted that the Supreme Court was preparing to pass on the case.

For the Alliance Defending Freedom and other religious freedom activists, the Masterpiece Cakeshop case and others like it seek a reaffirmation of the First Amendment's free exercise and free speech provisions in the face of shifting societal norms around sexual orientation. They don't oppose anti-discrimination protections for the LGBT community, but say that small business owners like Phillips shouldn't be forced to comply and contradict their religious beliefs.

"If any harm remains in leaving these wedding professionals free, it is only the tension we all face in living with people who disagree with us on the most personal matters," wrote Ryan Anderson, a senior fellow with the Heritage Foundation, in his analysis of the case for The Daily Signal.

However, legal experts on the other side of this debate say that no Americans should have a right to discriminate, even if they can point to religious teachings that justify their behavior.

"The basic question is whether David and Charlie and others throughout the country will be protected from discrimination," said Louise Melling, deputy legal director of the ACLU, on a Monday press call. She offered examples of the high court protecting persecuted groups from religiously motivated discrimination in the past, such as when it rejected private, religious schools' efforts to stop black students from enrolling.

The Supreme Court has agreed to hear the Masterpiece Cakeshop case at a time when support for business owners like Jack Phillips is dropping, according to a new analysis from Public Religion Research Institute.

Support for religiously based service refusals among all U.S. adults fell five percentage points from 2015 to 2016, the study reported. Only 3 in 10 Americans now support allowing small business owners to refuse services to the LGBT community, compared to 6 in 10 who oppose this policy.

Even among more conservative religious groups, such as Mormons and white evangelicals, support is dropping for small business owners with religious objections to serving gays and lesbians, as the Deseret News reported last week.

Members of these communities are likely swayed by the June 2015 Supreme Court ruling legalizing same-sex marriage and increased outreach to the LGBT community by faith leaders, said Robert Jones, CEO of Public Religion Research Institute.

"I think the Supreme Court decision being on the books made a difference," he said, noting that opinion shifts are also driven by younger members of these faith groups.

His organization's 2016 data marked the first time that no major religious group has a majority of members who favor religiously based service refusals.

The oral arguments for the Masterpiece Cakeshop case will be scheduled for sometime this fall. The Supreme Court's next term begins in October.

Email: kdallas@deseretnews.com, Twitter: @kelsey_dallas