It started over five years ago with a simple request for a wedding cake. And now, after wending its way through the system, Masterpiece Cakeshop v. Colorado Civil Rights Commission is finally having its day before the U.S. Supreme Court.

Many legal experts believe it will be the most significant case of the term. It involves a clash of our rights as citizens, as well as our ideals.

Two of the most precious rights Americans possess are freedom of expression and freedom to practice their religion as they see fit. Both are enshrined in the First Amendment.

But these rights are not absolute. They sometimes may clash with a duty toward others. Masterpiece Cakeshop will test these limits.

It began in July 2012, when Charlie Craig and David Mullins asked Jack Phillips, who owned the Masterpiece Cakeshop, to create a custom wedding cake to celebrate their same-sex marriage. Phillips refused, saying he didn’t wish to promote a same-sex wedding due to his religious beliefs.

One thing is for sure – no matter how it’s decided, the case will be a blockbuster.

Craig and Mullins filed a complaint with the Colorado Civil Rights Commission. The commission decided against Phillips, declaring he had discriminated on the basis of sexual orientation.

The commission ordered Masterpiece Cakeshop to change its policies, give its staff training on discrimination, and provide quarterly reports for two years on steps taken to comply with the order.

The Colorado Court of Appeals upheld the decision and the Colorado Supreme Court declined to hear the case. Last year, Phillips petitioned the U.S. Supreme Court, claiming the Colorado ruling violates the Free Speech and Free Exercise Clauses of the First Amendment.

The Supreme Court agreed to hear the case. Since then, almost a hundred briefs have been filed by groups around the country, arguing over the numerous potential legal ramifications.

Dr. John Eastman, a professor and former dean at Chapman University’s school of law, believes the free speech argument is strong, because Phillips’ work involved “expressive conduct.”

“Whether it’s a photographer, or a cake-maker, or a T-shirt designer,” he notes, “they’re engaged in expressive activity” which is covered by the First Amendment. In fact, in the case of “T-shirts or language on a cake, it’s actual speech.”

But Erwin Chemerinsky, dean of the law school at University of California, Berkeley, counters that the expressive activity comes from the customers. “If I choose the words on my cake, I’m engaging in expression. The baker is simply putting my words on a cake.”

Further, Chemerinsky notes that “even if this is about speech” that doesn’t mean the government can’t intercede. And in this case, “the interest in preventing discrimination outweighs” other interests. For instance, the baker would lose in court if he were “against interracial marriage and won’t bake a cake for an interracial couple.”

Eastman suggests we “shift the facts” and imagine a “white racist who wants an African-American baker to bake a cake celebrating the Ku Klux Klan.” If the courts tried to claim creating the cake “doesn’t implicate free speech rights, people would be howling.” Phillips was willing to serve homosexuals in his shop, but he didn’t want to be forced to support their beliefs.

As for the related free exercise of religion argument, Chemerinsky says that under the Supreme Court decision Employment Division v. Smith (1990), state law – such as Colorado’s anti-discrimination laws – may limit what people claim is their religious right, as long as the statutes are “neutral laws of general applicability” and not aimed at religion.

Eastman agrees that the Smith ruling makes the free exercise argument a tougher sell. But he wonders whether it’s time to revisit the precedent, now that Supreme Court Justice Antonin Scalia – who authored the opinion – has died.

Court observers believe the decision could go either way. They’ll be watching the newest justice, President Trump’s pick Neil Gorsuch, for signs of how he’ll vote. More importantly, most say, is which way Justice Anthony Kennedy goes. If it’s a close case, it’s generally thought he’ll most likely cast the deciding vote.

One thing is for sure – no matter how it’s decided, the case will be a blockbuster. Eastman believes this could be bigger than the Hobby Lobby opinion a few years back, which allowed a company an exemption from a contraceptive mandate due to religious objections. That case was limited in scope, but if the Supreme Court finds for Phillips, it could mean there’s a constitutional right that would trump numerous statutes across the nation.