An Oregon bakery fined $135,000 for refusing to serve a lesbian couple has appealed the decision to the Oregon Supreme Court.

In December, the Oregon Court of Appeals upheld a decision by the Oregon Bureau of Labor and Industries that found Aaron and Melissa Klein, owners of Sweet Cakes by Melissa, guilty of unlawfully discriminating against the couple when they refused to make a cake for the women's commitment ceremony.

Aaron Klein declined to make the cake for the women on January 17, 2013. Klein said he does not hate gays but that making a cake for a same-sex wedding would violate his faith. (At the time, Oregon had the nation's most robust domestic partnership law. Following a federal judge's ruling in May, 2014, Oregon became the 18th state to allow gay and lesbian couples to marry.)

In appealing the decision to the appeals court, the Kleins argued that the fine was excessive and the commissioner was biased against them, The Oregonian reported.

The Supreme Court has heard arguments in a similar case and a ruling is expected by June.

(Related: Anthony Kennedy sends mixed signals in “gay wedding cake” case.)