OKLAHOMA CITY - A legal fight is looming after the governor signed a controversial adoption bill into law. Backers say it protects an agencies freedom of religion, but opponents say it's nothing more than a license to discriminate, and they're taking a page out of a very conservative U.S. senator's playbook to fight it.

Kris Williams beamed with pride as she read the Mother’s Day message from her son. "You're an amazing mom. You're also a unicorn which is an amazing mythical creature.  But not as amazing as you are,” read Williams.

Williams and her girlfriend adopted the now 11-year-old after he had been horribly abused by his biological family for years. She said, often same sex parents can relate better to children who have been through the system.

"We know what it's like to be thrown away. And we know what it's like to be neglected. We know what it's like to be abused and so in that way we offer some specialty if you will when it comes to kids from hard places,” said Williams.

On Friday, May 11, Governor Fallin signed Senate Bill 1140, which would allow religious based adoption agencies to refuse to adopt to potential parents who don’t meet their religious or moral standards.

Backers say that allows religious based adoption agencies to continue to adopt children without worrying about the repercussions of following their faith.

"Basically, protects the system the way it is now. It doesn't change it. It doesn't ban anyone. It simply says if you are a faith-based service you can still participate in bringing families to the table,” said Diane Clay Arch Diocese of Oklahoma City.

But Pro-LGBTQ organization Freedom Oklahoma said it violates equal protection under the law, and they plan to sue.

Freedom Oklahoma is also looking into a veto referendum; an idea floated by former US senator Tom Coburn, a conservative from Oklahoma, to file a petition to veto the law at the ballot box. Coburn is spearheading a petition to have the largest tax increase in the state's history overturned by a ballot initiative.

"It's something that we're perusing actively. We're looking at polling and what we can do and we're planning to fight this on every front we can,” said Troy Stevenson with Freedom Oklahoma.

The veto petition would require about 42,000 signatures to put on to the November ballot.