At issue in the complaint from David Mullins and Charlie Craig against Masterpiece Cakeshop in suburban Denver is whether religious freedom can protect a business from discrimination allegations from gay couples.
Mullins and Craig wanted to buy a cake last year, but when one of the shop owners, Jack Phillips, found out the cake was to celebrate a gay wedding, he turned the couple of away and cited his religious faith.
"(His) faith, whatever it may have to say about marriage for same-sex couples or the expressive power of a wedding cake, does not give the respondents a license to discriminate," Amanda Goad, an attorney with the American Civil Liberties Union, told an administrative judge in Colorado's Civil Rights Commission.
Phillips' attorney, Nicolle Martin, said her client shouldn't be forced to ignore his Christian faith while running the business he's had for nearly 40 years. She said Phillips feels "privileged to design and create the cakes that celebrate the joyous events of people's lives."
"He believes this is a vocation chosen for him by God, and as a man of God, Jack Phillips lives by certain biblical principles," Martin said.
She said Phillips faces up to a year in prison if the court rules against him and he continues to refuse to make wedding cakes for gay couples.
Judge Robert N. Spencer said he would issue a ruling later this week.
The ACLU in Colorado filed the discrimination complaint on behalf of Mullins, 29, and Craig, 33, who were married in Massachusetts and planned to celebrate their wedding in Colorado.
A similar case is pending in Washington state, where a florist is accused of refusing service for a same-sex wedding. In New Mexico, the state Supreme Court ruled in August that an Albuquerque business was wrong to decline to photograph a same-sex couple's commitment ceremony.
Colorado has a constitutional ban against gay marriage, but allows civil unions. The civil union law, which passed earlier this year, does not provide religious protections for businesses - a provision Republicans wanted. Democrats argued that such a provision would give businesses cover to discriminate in violation of state law.
"Here, the discrimination was based on who the customers were, and that's what Colorado clearly prohibits," Goad said.
Martin has said the case is about religious conscience and that one person's beliefs shouldn't be held above someone else's. She told the judge that Phillips "has a right not to spread a message with which he disagrees."