A Southern California school board at odds with state officials and local residents this summer over its rejection of social studies curriculum that includes gay rights is now being sued regarding a different policy decision.

A coalition of parents, students, teachers and a union representing public education officials in Temecula, California, are suing their school board and district for implementing a critical race theory ban in December 2022, according to a lawsuit filed Wednesday.

"Now more than ever, the health of this nation's democracy depends on public school classrooms that serve as a marketplace of ideas rather than banning ideas with which it disagrees," Amanda Mangaser Savage, one of the attorneys representing the case, said during a Wednesday news conference. "The board should be encouraging students to weigh competing viewpoints and think for themselves."

The Temecula Valley Unified School District's implementation of Resolution 21 bans anyone in the district from teaching critical race theory and "doctrines derived from Critical Race Theory," the resolution says.

The lawsuit says the "vague resolution 'hinders Temecula educators' ability to teach State-mandated content standards, prepare for the coming academic year, and support rather than stifle student inquiry."

The attorneys for the plaintiffs argue the Board's actions violate California law, the right to due process and the right to be free from discrimination on the basis of race, sex, and sexual orientation, among other claims. The plaintiffs are requesting an order declaring the resolution to be unconstitutional and enjoin the board from implementing or enforcing it, as well as requesting costs and attorney's fees, the lawsuit says.

The lawsuit comes after the school board voted 3-2 on May 16 to not use a new state-endorsed social studies textbook and curriculum that was piloted by the district, saying there was not enough parental involvement in the creation process and making comments attacking gay rights advocate and politician Harvey Milk. The school board ultimately voted to use the books after California Gov. Gavin Newsom threatened to levy a $1.5 million dollar fine.

During Wednesday's news conference, some of the teachers participating in the lawsuit read statements from student plaintiffs, who are using pseudonyms since they are minors.

"After implementing the resolution, productive conversations around racism, prejudice and bigotry were absent from almost all of my classrooms," teacher Jennifer Scharf said speaking on behalf of Gwen S., who are both plaintiffs in the lawsuit.

"Additionally, I've noticed teachers have been less likely to confront students for making negative or ignorant comments about other identities. Having controversial and heavy discussions in a safe class environment teaches students how to respect different ideas."

The attorneys will be asking for a preliminary injunction as part of their next steps, "seeking to strike down this resolution as unconstitutional," Mangaser Savage said.

CNN has reached out to the Temecula school district and the five board members for comment.

Board member Steven Schwartz -- who has been a supporter of the state-endorsed textbooks and curriculum -- told CNN that he is not surprised by the lawsuit as the board members were previously warned about an impending lawsuit unless they rescinded the resolution and accepted the piloted textbooks.

"I thought it was a mistake from the beginning, it's part of a political agenda and has nothing to do with education," Schwartz said, adding that "it's not what we were elected to do."