Washington charter schools unveiled their new weapon in the legal battle to protect their schools. Tuesday, a dozen charter school families filed a motion to intervene in a lawsuit accusing the schools of being unconstitutional.

"Both of my students would have fallen through the cracks in the traditional public school," said Crystal Swaffer, one of the interveners.

Swaffer has twin boys with unique challenges. One has sensory issues. Both are exceptionally bright. Challenges she said that are well met by Soar Academy, a charter school in Tacoma.

"Just the ability to individualize their needs has just been amazing," she said.

Swaffer joins 11 other families who share her frustration with the charter school battle going on in Washington state for years.

"Why are we spending our time and energy trying to keep these kids out of schools they really want to attend?" said former state attorney general Rob McKenna.

On behalf of the families, McKenna filed a motion to intervene in a lawsuit that attacks the state's latest charter school law. They're want to join Washington state as defendants in the suit.

In 2012 voters approved charter schools in Washington state, but the state supreme court declared them unconstitutional and unable to received public funding. So earlier this year, the legislature passed a law changing the funding source.

In response, the state teachers union filed another lawsuit in August, along with El Centro De La Raza, and the League of Women Voters claiming the law still diverts public money.

But the charter school families said they're the true stakeholders in this fight unlike the plaintiffs in the case.

"Everyone who lives in Washington state has a stake in this issue because it's the state's paramount duty to fully fund public education for all of our state's kids," said WEA spokesperson Rich Wood.

McKenna believes the teacher's union opposes charter schools because it doesn't want to give up control.

"They feel like they don’t have a say in how they're run. They don't like the lack of control of the independence of these schools under a state commission instead under the WEA and the local school board. I think it's that simple," McKenna said.

As both sides continue to fight over school choice and school funding, charter schools remain open for now.