Debbie Munn's son was planning the happiest day of his life. Then, he was turned away -- because of who he loves.

Five years ago, Dave Mullins and Charlie Craig walked into Masterpiece Cakeshop, a Lakewood, Colorado, bakery to purchase a cake for their wedding reception. But the bakery’s owner refused to serve them solely because they’re a same-sex couple.

Colorado courts found that the bakery discriminated against Dave and Charlie, violating a state law that says businesses open to the public can’t turn away customers based on sexual orientation. Now, the bakery is asking for a “constitutional exemption” —permission to violate the state law based on the owner’s objection to serving gay people.