Please see https://www.usac.org/e-rate/applicant-process/starting-services/cipa/ for details.
The Children's Internet Protection Act (CIPA) requires that schools and libraries implement Internet safety policies in order to receive federal technology funding such as E-Rate discounts. This Internet safety policy must include filtering or another "technology protection measure" that blocks access to "visual depictions" of obscene material, child pornography and material that is "harmful to minors".