WASHINGTON (CBSNewYork/AP) — Hairstylists, jewelers, chefs, florists, invitation designers and makeup artists were all part of the discussion at the Supreme Court as the justices took up the case of a Colorado baker who refused to make a wedding cake for a same-sex couple.

The justices will decide if baker Jack Phillips violated an anti-discrimination law or if he was exercising his Constitutional rights to free speech and freedom of religion.

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The argument was the first involving gay rights since the Supreme Court ruled in 2015 that states could not prevent same-sex couples from marrying.

Phillips, citing his religious beliefs, refused to make a cake for Dave Mullins’ and Charlie Craig’s wedding back in 2012.

“I serve everybody who comes into my shop so in this case, I would gladly sell you anything in my shop but this is just an event that I can’t create a cake for,” he told CBS News.

Phillips told CBS News his cakes are personal artistic expressions, but to Mullins and Craig, it was discrimination and they filed a complaint against Phillips.

“What we went through was humiliating and painful and degrading and we didn’t want another loving couple to have to go through that,” Mullins said.

Protesters on both sides filled the sidewalk in front of the court, shortly before the start of the argument.

“We got Jack’s back,” Phillips’ supporters said. Backers of Craig and Mullins countered: “Love wins.”

The Trump administration is supporting Phillips in his argument that he can’t be forced to create a cake that violates his religious beliefs. It appears to be the first time the federal government has asked the justices to carve out an exception from an anti-discrimination law.

The case’s outcome also could affect photographers and florists who have voiced objections similar to those of Phillips.

“Artists shouldn’t be forced to express what the government dictates. The commission ordered Jack to celebrate what his faith prohibits or to stop doing the work he loves. The Supreme Court has never compelled artistic expression, and doing so here would lead to less civility, diversity, and freedom for everyone, no matter their views on marriage,” Kristen Waggoner, the Alliance Defending Freedom who is representing Phillips, said in an email.

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But the American Civil Liberties Union and other rights groups that have sided with the gay couple said they fear a ruling for Phillips could allow for discrimination by a range of business owners. They said the court has never recognized what they call a constitutional right to discriminate.

“The question is whether a shop like Masterpiece Cakeshop can put up a sign in its window saying, ‘Wedding cakes for heterosexual couples only,'” ACLU deputy legal director Louise Melling said. The ACLU is representing Craig and Mullins.

During the first half of oral argument on Tuesday the justices questioned an attorney for Phillips, who made the First Amendment argument.

But Justice Elena Kagan wanted to know “how do you draw a line?” about what counts as speech. Kagan wanted to know: “Why is there no speech in creating a wonderful hairdo?” and “Where would you put a tailor?”

Justice Sonia Sotomayor told Phillips’ attorney: “The primary purpose of a food of any kind is to be eaten.”

Meanwhile, all eyes were on Justice Anthony Kennedy throughout the 75-minute argument. The 81-year-old Kennedy is the author of the 2015 gay marriage decision and all the court’s major gay-rights rulings. At the same time, Kennedy has forcefully defended free-speech rights in his nearly 30 years as a justice.

Kennedy worried early in the argument that a ruling in favor of baker Jack Phillips might allow shop owners to put up signs saying “We do not bake cakes for gay weddings.”

But later, Kennedy said the Colorado Civil Rights Commission seemed “neither tolerant nor respectful of Mr. Phillips’ religious beliefs” when it found his refusal to bake a cake for the gay couple violated the state’s anti-discrimination law.

Colorado native Neil Gorsuch also will be taking part in the most important gay rights case since he joined the Supreme Court in April.

Colorado is among only 21 states with statewide laws barring discrimination against gays and lesbians in public accommodations.

The case, Masterpiece Cakeshop v. Colorado Civil Rights Commission, 16-111, will be decided by late June.

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(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)