The Supreme Court case on same-sex wedding cakes hinges on a single question: Is food art?

Five years ago, a Lakewood, Colorado baker named Jack Phillips refused to bake a cake for the same-sex wedding of Craig and David Mullins because, he said, it was against his religious beliefs. When the couple learned Phillips’ refusal to serve them on the basis of their sexual orientation violated the state’s public accommodation law, they filed a civil rights complaint with a state commission. (These are laws at both the federal and state level that prohibit discrimination against protected groups in businesses that are, in general, open to the public.) The commission sided with the couple. So did a state appeals court. Then Phillips took his case to the Supreme Court.

Masterpiece has evolved into a clash between Colorado’s anti-discrimination laws and what Phillips says is his protected freedom of speech. Being forced to express a point of view that runs counter to his personal beliefs, he claims, is a violation of his right to freely exercise his religion.

But the religion portion of this story is the backdrop of another, possibly more unlikely free speech argument. Back to that food-as-art bit: Philips and his advocates have been making the case that his business isn’t a service that can be controlled and regulated by public accommodation laws, and open to all people, as much as it is a form of personal “expressive conduct.” And not just any expressive conduct. The very first line of his petition to the high court: “Jack Phillips is a cake artist.”

When the case was still in Colorado, a concerned coalition of bakers filed an amicus brief showing that Phillips was not alone. Let’s say he was a member of the, uh, Frosting School of food artists, a national movement active earlier this decade, whose zenith was Cake Boss. The brief is filled with examples of super-involved, elaborately designed cakes the coalition of bakers use to help make the argument that Phillips’ cakes are indeed works of art, the kind that is regularly protected by freedom of speech laws. The kicker? Their suggestion that Phillips might even “create cakes without any specific function solely for the sheer beauty or challenge.” L’art pour l’art.

Those are the grounds under which Philips’ lawyers will be asking the Supreme Court to excuse or exempt him from the Colorado law. But whether or not baking a cake is truly expressive conduct, falling under the umbrella of the First Amendment, is the critical question.

Now, let’s suppose the court rules that cake baking is, in fact, not a business service but a form of personal expression. Danielle Weatherby, a law professor at the University of Arkansas, says that would set a precedent allowing other bakers, cooks, or food makers—no matter how large—to claim their products are works of art, and therefore, as forms of speech that can’t be controlled by public accommodation laws.

“I think that’s a dangerous precedent to set,” says Weatherby. “I don’t mean to sound dramatic, but it could lead to a system where a large portion of service providers won’t serve a particular group of individuals.”

That’s Weatherby’s opinion. In the event of a victory, The New Yorker disputes the notion that the products of large corporations—like, say, a McDonald’s Egg McMuffin—will be granted the same latitude as Phillips’ specialized works of art. Indeed, the issue of customization is key. Recently, a Brooklyn judge ruled that baking baklava didn’t quality as a creative act, essentially because it was made on an assembly line. That forced a Turkish food seller to pay its workers years of overtime pay.

Above all, the case could have major implications for anti-discrimination laws, particularly when it comes to protecting members of the public from discrimination based on their sexual orientation or gender identity. When being served at a business, Americans of all races, colors, national origins, and religions have been covered under these laws since the passage of the Civil Rights Act of 1964, no matter what state we’re in.

Sexual orientation, however, is protected in only 21 states, and the District of Columbia.

Since the Civil Rights Act was passed, business owners haven’t been able to plausibly use freedom of speech to trump anti-discrimination laws. Legal observers have noted the similarities between Masterpiece and other Supreme Court cases, including Katzenbach v. McClung (1964) and particularly Newman v. Piggie Park Enterprises, Inc. (1968). In that case, the defendant, who owned a chain of South Carolina barbecue restaurants, claimed that he couldn’t serve black customers because racial intermingling violated his religious beliefs. He lost.

If the Supreme Court eventually rules in favor of Phillips, and his freedom of speech is deemed to exempt him from anti-discrimination laws, the case will be (and already is) about way more than cake: LGBTQ advocates worry it could kick open the door to further exemptions.

“The Supreme Court decided long ago that businesses that are open to the public should be open to everyone,” says Sarah D. Gordon, an attorney with the Washington, D.C. law firm Steptoe & Johnson, which filed an amicus brief, signed by 37 companies—from Apple to Pfizer—in support of the defendants. Those companies don’t want their employees discriminated against in their communities. (Nor, she added, do they want to have to sort through the headache of figuring out what, in a post-cake world, would constitute “expressive conduct.”)

It’s hard to know what Phillips’ chances are of actually winning. Until now, other small businesses that do a lot of wedding work—like a Washington florist, and two photographers in New Mexico—haven’t been able to convince the lower courts to exempt them from state accommodation laws. But they’re waiting in the wings if the justices side with the baker.

For what it’s worth, the Department of Justice in September voluntarily weighed in on the case, taking what Weatherby, the law professor, calls the “unusual” step of siding against Colorado.