(CNN) The Supreme Court wrestled with a clash between religious freedom and LGBT rights on Tuesday as it heard arguments from a Colorado baker who refused to make a cake to celebrate a same-sex couple's marriage because he believes that God designed marriage to be between a man and a woman.
During lively arguments that lasted over the 60 minutes allotted, the liberal justices, joined at one point by crucial swing vote Justice Anthony Kennedy, questioned where the line could be drawn should it side with Masterpiece Cakeshop owner Jack Phillips.
As a lawyer for Phillips made his free speech argument on behalf of the baker's "artistic expression," Justice Elena Kagan and other liberals pounced, asking where they were supposed to draw a coherent line designating which business owners could qualify to claim an exemption from anti discrimination laws. A jeweler? A makeup artist? A hair stylist?
When Solicitor General Noel Francisco stood to argue in support of Phillips, Kennedy asked him if he prevailed could a baker put a sign in a window saying "we don't bake cakes" for same-sex weddings.
But Kennedy seemed torn. At another point he said he worried about a "hostility" toward religion. He asked whether the state of Colorado had been "tolerant" of Phillips' religious beliefs.
The case pits the religious liberty claims of Phillips, against the couple, David Mullins and Charlie Craig, who say Phillips' actions amount to discrimination.
LGBT rights advocates fear that if the Supreme Court ultimately sides with Phillips, it will diminish its landmark opinion from two years ago that cleared the way for same-sex marriage nationwide. Both sides agree that a ruling in favor of Phillips would also open the door to claims from others who engage in professional services -- florists, for example -- to claim that their religious liberty exempts them from public accommodation laws applicable to other businesses.
It was back in 1993 that Phillips opened the bakery, knowing at the outset that there would be certain cakes he would decline to make in order to abide by his religious beliefs. "I didn't want to use my artistic talents to create something that went against my Christian faith," he said in an interview, noting that he has also declined to make cakes to celebrate Halloween.
Flash forward to 2012, when same-sex marriage was not yet legal in Colorado, but two men walked into the bakery.
"The conversation was fairly short," Philips remembered. "I went over and greeted them. We sat down at the desk where I had my wedding books open."
The men told Phillips they wanted a cake to celebrate their planned wedding, which would be performed in another state. Phillips said he knew right away that he couldn't create the product they were looking for without violating his faith.
"The Bible says, 'In the beginning there was male and female,'" Phillips said. He offered to make any other baked goods for the men.
"At which point they both stormed out and left," he said.
The couple filed a complaint with the Colorado Civil Rights Commission, which ruled in their favor, citing a state anti-discrimination law. Phillips took his case to the Colorado Court of Appeals, arguing that requiring him to provide a wedding cake for the couple violated his constitutional right to freedom of speech and free exercise of religion. The court held that the state anti-discrimination law was neutral and generally applicable and did not compel Masterpiece to "support or endorse any particular religious view." It simply prohibited Phillips from discriminating against potential customers on account of their sexual orientation.
Phillips then took his case to the Supreme Court and the justices agreed to take it up after mulling it for several weeks.
In court papers, Kristen K. Waggoner, a lawyer from the conservative Alliance Defending Freedom who is representing Phillips, argued that the First Amendment guarantees him the right to decline to make wedding cakes that celebrate marriages that are in conflict with his religious beliefs. She said that Phillips is protected by two parts of the First Amendment: its protections of religious exercise and free speech. While she argued that the free exercise clause forbids the commission from targeting Phillips "and like-minded believers for punishment," she reserved the bulk of her brief for the free speech clause, perhaps targeting Kennedy, who has at times shown an expansive view of free speech.
Waggoner argued that a person viewing one of Phillips' custom wedding cakes -- his "artistic expression" -- would "understand that it celebrates and expresses support for the couple's marriage." She said the Supreme Court's compelled speech doctrine "forbids the commission from demanding that artists design custom expression that conveys ideas they deem objectionable."
In the interview, Phillips said, "I feel I'm being compelled to create artwork for an event -- an inherently religious event -- that goes against my faith, and I'm being compelled to do so under penalty of jail time and fines."
Not surprisingly, Mullins and Craig see the case through an entirely different lens: discrimination.
"This case is about more than us, and it's not about cakes," Mullins said in an interview. "It's about the right of gay people to receive equal service."
"This isn't about artistic expression," said Craig. "I don't feel like we asked for a piece of art, or for him to make a statement, we simply asked him for a cake, and he denied that to us simply because of who we are."
The couple is being represented in court by the American Civil Liberties Union.
"In essence, the bakery seeks a constitutional right to hang a sign in its shop window proclaiming, 'Wedding Cakes for Heterosexuals Only,'" the ACLU's David D. Cole wrote in court briefs.
Cole said that whether a cake is an artistic expression is not at issue. "The question, rather, is whether the Constitution grants businesses open to the public the right to violate laws against discrimination in the commercial marketplace if the business happens to sell an artistic product." The answer, Cole contends, is "no."
Twenty other states and the District of Columbia likewise expressly prohibit places of public accommodation from discriminating on the basis of sexual orientation, according to the National Conference of State Legislatures.
The Trump administration sides with Phillips in the case, arguing that it falls "within the small set of applications of content-neutral laws that merit heightened scrutiny" from the courts. "A custom wedding cake is not an ordinary baked good; its function is more communicative and artistic than utilitarian," Solicitor General Noel Francisco argued. "Accordingly, the government may not enact content-based laws commanding a speaker to engage in protected expression: An artist cannot be forced to paint, a musician cannot be forced to play, and a poet cannot be forced to write."
But the government lawyers did draw a line when it comes to race, arguing that laws targeting race-based discrimination may survive heightened First Amendment scrutiny in part because racial bias "is a familiar and recurring evil that poses unique historical, constitutional and institutional concerns."