The Supreme Court on Monday left in place a lower court opinion that invalidated a code of conduct at a North Carolina publicly funded charter school that required girls to wear skirts in order to "preserve chivalry" based on the belief that every girl is a "fragile vessel."

A federal appeals court had previously held that the school, Charter Day, violated the Constitution's Equal Protection Clause in enforcing the requirement and concluded that the school was a state actor with respect to its student code of conduct.

"We observe that nothing in the Equal Protection Clause prevents public schools from teaching universal values of respect and kindness," the United States Court of Appeals for the 4th Circuit held.

"But those values are never advanced by the discriminatory treatment of girls in a public school," the majority wrote, adding that the "skirts requirement blatantly perpetuates harmful gender stereotypes as part of the public education provided to North Carolina's young residents."

The lawsuit was originally brought by parents of three students who filed a federal lawsuit, arguing that the policy violated the Equal Protection Clause as well as Title IX, a federal law that prohibits discrimination based on sex in schools that receive federal funds.

They had requested a change in the uniform policy to allow girls to wear pants or shorts, as boys at the school do. Their lawyers at the American Civil Liberties Union said that the skirt requirement "restricted girls' movement and that wearing pants or shorts would allow them to be more active during recess, avoid exposing their underwear when they crawled during tornado and fire drills, and keep them warmer in winter."

Lawyers for the school appealed the decision to the Supreme Court, arguing that North Carolina authorizes private nonprofit corporations to operate charter schools that are open to all, tuition-free and publicly funded as an alternative to traditional, government-run public schools.

They argued that charter school operators are "broadly empowered to devise educational policies ... without state coercion," and that the policy was "desired by parents who choose to send their children to the school."

The policy was implemented at the founding of the school and required all students to wear "white or navy-blue tops, tucked into khaki or blue bottoms. Boys must wear pants or shorts with a belt, must keep their hair short and not wear any jewelry. Girls must wear jumpers, skirts or skorts, not have no hair-length restrictions and may wear jewelry."

"The Uniform Policy was designed to foster classroom discipline and mutual respect between boys and girls," the school argued in court papers.