AN LGBTQ ADVOCACY group in the US has sued Florida Governor Ron DeSantis in an attempt to block a new law forbidding classroom instruction on sexual orientation and gender identity from pre-school through to third grade.

The law has catapulted Florida and DeSantis, a potential 2024 Republican presidential candidate, to the forefront of the country’s culture wars. Critics call it the “Don’t Say Gay” law and argue that its true intent is to marginalise LGBTQ people and their families.

The challenge filed in federal court in Tallahassee by the National Centre for Lesbian Rights on behalf of Equality Florida and Family Equality alleges the law violates the First Amendment and other provisions of the US Constitution.

A statement announcing the lawsuit says the law deliberately employs broad terms and invites arbitrary and discriminatory enforcement, empowering parents to be roving censors who can sue school boards for damages based on any perceived violation.

The law states: “Classroom instruction by school personnel or third parties on sexual orientation or gender identity may not occur in kindergarten through grade 3 or in a manner that is not age appropriate or developmentally appropriate for students in accordance with state standards.” Parents would be able to sue districts over violations.

Mr DeSantis and other Republicans have repeatedly described the rules as reasonable, saying children should learn about sexual orientation and gender identity from their parents, not in schools.

“We will make sure that parents can send their kids to school to get an education, not an indoctrination,” the governor said when he signed it into law this week.

Many critics have said the law’s language, particularly the phrases “classroom instruction” and “age appropriate,” could be interpreted so broadly that discussion in any grade could trigger lawsuits, creating a classroom atmosphere where teachers would avoid the subjects entirely.

Intense public backlash followed the Bill’s introduction in Florida’s Republican-controlled legislature this year, with the White House, Hollywood celebrities, students, Democrats and LGBTQ advocates condemning the policy. Legal challenges have been expected.

The suit says the law is unconstitutionally vague and discriminatory and violates First Amendment rights to free expression.

“Already, our children have told us that they are afraid that they will not be able to talk about their parents at school,” Dan and Brent VanTice, parents of two first-grade students, said in the statement announcing the suit. “We are heartbroken that our children are already feeling isolated and stigmatised by this law.”

The law adds fuel to a persistent feud between DeSantis and Democratic President Joe Biden, who tweeted after DeSantis signed the Bill this week that “My Administration will continue to fight for dignity and opportunity for every student and family — in Florida and around the country.”