After lower courts upheld a Phoenix ordinance that prohibits discrimination based on sexual orientation and gender identity, a Christian law firm has appealed to the Arizona Supreme Court.

Alliance Defending Freedom (ADF) represents Joanna Duka and Breanna Koski, owners of Brush & Nib Studio, which specializes in custom wedding invitations, in their claim that Phoenix's ordinance conflicts with their religious beliefs and violates their freedom of speech and religion.

Last month, the Arizona Court of Appeals ruled against their attempt to invalidate the city's ordinance.

“[A]llowing a vendor who provides goods and services for marriages and weddings to refuse similar services for gay persons would result in 'a community-wide stigma inconsistent with the history and dynamics of civil rights laws that ensure equal access to goods, services and public accommodations,'” the three-judge panel wrote.

Attorney Samuel Green argues that the women's work is speech and that “a law compelling art compels speech.”

Other Arizona communities with similar ordinances include Tucson, Tempe and Flagstaff, all of which would be affected if Phoenix's law were struck down by the state's highest court.

The Arizona Supreme Court has yet to act on the petition.