A county clerk in Kentucky argued Monday that she has a First Amendment right to refuse to issue marriage licenses to gay and lesbian couples.

The American Civil Liberties Union (ACLU) of Kentucky filed a class action lawsuit against Rowan County Clerk Kim Davis after she decided to stop issuing marriage licenses to all couples rather than serve gay couples.

Plaintiffs in the case are four couples who were refused a license from Davis' office. Half of the couples are gay.

Following the Supreme Court's ruling striking down marriage bans in all 50 states, Davis pledged never to issue a marriage licenses to a gay couple, saying it would be a violation of her Christian faith.

“It's a deep-rooted conviction; my conviction won't allow me to do that,” Davis said. “It goes against everything I hold dear, everything sacred in my life.”

Appearing in court Monday, Davis testified that she prayed and fasted for months over what would be her response to the court's decision.

She said that the First Amendment of the U.S. Constitution gives her the right to refuse to serve gay couples because it violates her religious faith.

A decision in the case is expected by the middle of August.