Schools across the country have denied students entry to prom, graduation ceremonies and other school activities because of dress code policies that advocates say disproportionately impact LGBTQ+ students and girls.

In May, 16-year-old Florida junior Sophie Savidge told NBC News that she wasnt allowed to go to prom because she wore a suit. In a statement at the time, the school pointed to its online guide to attire, which stipulates that ladies are required to wear dresses and one piece attire only to formal events.

A transgender student in Alabama reportedly wasnt allowed to go to her senior prom in April because she wore a dress. The schools student handbook said that it was up to administrators to deem appropriate clothing or appearance, according to AL.com.

And the American Civil Liberties Union of Mississippi filed a federal complaint with the Department of Education against Harrison County School District for barring a transgender girl from wearing a dress to her regional band concert this spring. The complaint detailed a two-year pattern of the district punishing girls transgender and cisgender alike for violating dress codes requiring students to dress in clothes that are consistent with their biological sex.

The school district added the provision of biological sex to its dress code after LGBTQ+ students complained that they couldnt wear clothes that expressed their gender identity, said Liza Davis, a fellow at the ACLUs Womens Rights Project.

School administrators have long used dress codes to enforce a rigid gender binary and uphold different standards based on assigned sex. This year, there has been a renewed effort in school districts across GOP-led states to enforce policies that are more explicitly restrictive to queer, trans and gender nonconforming students, as a record number of anti-LGBTQ bills have been introduced in statehouses across the country.

Requiring students to dress according to their biological sex even if it seems to be neutral as a rule, and its not calling out any particular student has a disproportionate impact on gender nonconforming, nonbinary and transgender students because it is tying gender expression to their sex assigned at birth, essentially, Davis said.

Students who are targeted over dress code infractions can lose out on class time or face punishments like suspension, and may face emotional distress from being pulled from class and told to change, she said.

Sex-based dress codes often force boys to wear pants and girls to wear skirts or dresses of a certain length. Advocates say these rules push rigid gender stereotypes and outdated, misogynistic ideas of how girls should dress in the presence of boys. And they leave no room for less traditional gender expression.

School dress codes that rely so heavily on biological sex are reminiscent of anti-LGBTQ bills and policies across the country.

The districts discriminatory dress code policies and enforcement are part of a wider sex-based hostile environment, which has impacted our clients and other students, Davis said, referring to the complaint in Mississippi.

Policies that purport to bring clarity to sex discrimination laws by codifying definitions of male and female in order to exclude trans people from those categories often use exceedingly specific language that also fails to account for intersex people. The language embedded in these policies, often called Womens Bill of Rights bills , was first proposed by Independent Womens Voice, a conservative organization that has argued its necessary to protect women-only spaces and activities from trans peoples inclusion.

So far this year, at least 10 states have introduced or passed similarly worded legislation to narrowly define biological sex based on a persons reproductive capacity or chromosomes. Oklahomas governor just signed the states own version of a Womens Bill of Rights into law on Monday. Last year, Rep. Debbie Lesko (R-Ariz.) introduced a Womens Bill of Rights resolution to Congress, though its made no progress since.

Some state-level legislation now includes definitions of sex that explicitly bar trans people from updating their drivers licenses or state IDs, which makes it harder to vote , travel, and exist in public life.

Advocates say that an emphasis on biological sex has negative ramifications for all people, including cisgender women, because it encourages people to police one anothers gender including kids. People have harassed child athletes who they suspect are transgender, and one state official in Utah came under fire for falsely suggesting that a student was transgender because of how she looked.

Sex and gender researchers previously told HuffPost that binary definitions of sex do not reflect how scientists currently understand human sex, which is determined by a variety of biological phenomena including hormones, genitals and otter secondary sex characteristics.

As more and more anti-LGBTQ legislation specifies how LGBTQ+ students can and cannot express themselves and participate in school activities, Davis said she would not be surprised if we see more schools across the country adopt policies that have explicit biological sex provisions.

Those kinds of provisions are likely to violate Title IX, a 1972 federal law that protects against discrimination on the basis of sex in public schools and colleges, Davis said.

The Biden administration released long-awaited final guidance for Title IX this spring, expanding the definition of sex discrimination to include sexual orientation and gender identity. Since then, more than a dozen red states have sued the Department of Education and vowed to not comply with this updated interpretation.

Many protections for LGBTQ students now hang in the balance . Presumptive Republican presidential nominee Donald Trump has vowed to overturn Title IX and restrict Title VII, which prohibits discrimination on the basis of sexual orientation and gender identity, on day one of his second term if elected.

The country has to decide. Do we want to live in a place that looks like some of the most regressive politics in the states where right wing elected officials have control over everything: the way you dress, how you identify, the name and pronoun you use, what bathroom youre able to access? Brandon Wolf, press secretary at the Human Rights Campaign, told HuffPost earlier this spring. Or do we want to live in a country... where we have the freedom to be ourselves, we have the freedom to make decisions about our own bodies?