In 1972, the United States District Court for the Eastern District of Pennsylvania decided the case of Pennsylvania Association for Retarded Citizens (PARC) v. Commonwealth of Pennsylvania, hereafter PARC v. Pennsylvania. The court ruled that the state could not deny an individual's right to equal access to education based on an intellectual or developmental disability status. PARC brought the case against the state of Pennsylvania on behalf of fourteen families with intellectually disabled children who were unable to access to public schools based on their child’s disability. PARC challenged state laws that permitted schools to deny education to children who do not reach the mental age of five, or the average intelligence of people aged five, by the time they begin first grade. Both sides settled following the testimony of expert witnesses on PARC's behalf, and the US District Court approved the consent decree. PARC v. Pennsylvania was one of the first cases to establish that people born with an intellectual disability should have the same access to education as the rest of the population.

In Mills v. Board of Education of District of Columbia (1972), the United States District Court for the District of Columbia held that students with disabilities are entitled to an education, and that education cannot be denied based on the accommodations’ additional cost to the school. Mills was a class action lawsuit brought to the court on behalf of seven children denied public education by the District of Columbia School District because of their disabilities and the cost of accommodations the school would incur to educate them. US District Court Judge Joseph Cornelius Waddy presided over the case and ruled in favor of the students, finding that they were not given due process prior to expulsion from the school. Mills was one of the first cases in the US that guaranteed the right of students with any disability to a public education, regardless of the cost to the school system, and led to comprehensive federal legislation protecting disabled children's right to free public education.

In 1975, the United States Congress passed the Individuals with Disabilities Education Act, referred to as the IDEA, which codified the right of all American children to a free and appropriate public education regardless of disability status. The IDEA requires all public schools that accept federal funds to provide education that meets the needs of students with disabilities at the public expense. Prior to IDEA, many students with disabilities went without any educational opportunities, and many faced confinement in institutions. The IDEA enshrined the right to education for children with disabilities, allowing millions of children to learn in a public-school classroom by setting guidelines for accessibility and the instruction of students with disabilities in American public schools.