Schools often have a dress code that requires school uniforms or that limits clothing styles—such as policies of no tank tops, shorts, low-cut tops, pants worn below the waistline, or suggestive, provocative, or controversial messages. Some schools extend these dress code policies to hairstyles, headwraps, hair color, and facial hair.

These policies are sometimes challenged by students on free speech grounds (under the First Amendment to the U.S. Constitution) and on discrimination grounds. Schools are required to meet a high burden to justify restricting their students’ right to freedom of speech.

Each school policy and claim of a violation of law must be evaluated on a case-by-case basis but schools are generally allowed to restrict clothing, speech, and hairstyle choices only if they would likely disrupt the educational environment of the school and interfere with school activities—including by causing tension and discord among the students or teachers.

In Illinois, schools are permitted to implement dress codes and uniform policies, which may include restrictions on clothing styles, hairstyles, headwraps, hair color, and facial hair. However, these policies must not infringe upon students' First Amendment rights to free speech or be discriminatory in nature. When students challenge these policies, schools must demonstrate that the restrictions are necessary to prevent disruption to the educational environment or interference with school activities. The standard used to assess the validity of such policies is whether the restricted expression would likely cause substantial disruption or material interference with school operations. This standard comes from the landmark U.S. Supreme Court case Tinker v. Des Moines Independent Community School District (1969). Illinois schools must also ensure that dress code policies are applied in a non-discriminatory manner, consistent with both state and federal anti-discrimination laws. Each case involving a challenge to a school's dress code policy is evaluated individually to determine if the school's actions are legally justified.