In North Carolina, a school cannot require its female students to wear skirts, according to a lower court decision that was upheld by the US Supreme Court.
The school's uniform policies were found to have violated the constitutional rights of its female students by a US federal court last year.
The Charter Day school in Leland, Minnesota, appealed the decision all the way to the highest court in the land.
The justices rejected the appeal without making a statement.
The dress code at the school has already been modified to permit girls to wear trousers.
The school's founder, Baker Mitchell, argued in court documents that the skirts were necessary to uphold "chivalry," which he defined as "a code of conduct where women are regarded as a fragile vessel that men are supposed to take care of and honor.".
The policy, he continued, would guarantee that female students were treated "courteously and more gently than boys.".
However, a group of parents contested the rule, claiming it unfairly disadvantages their daughters when compared to their male counterparts.
The equal protection clause of the Constitution's 14th Amendment, which forbids the enactment of laws that are arbitrarily discriminatory, was violated by the dress code, according to the ruling of the 4th US Circuit Court of Appeals in June 2022.
Charter Day's dress code, according to the majority opinion written by Senior Circuit Judge Barbara Milano Keenan, "could perpetuate stereotypes with potentially disastrous consequences for young girls.".
Charter schools, a small portion of the US educational system, are financed by taxpayers but are independently run.