Commonly referred to as PL 94-142, this federal law required free public education be available to each child with a disability.
This law allowed for children, who were previously denied, to receive an education. It also created a foundation of expectations that future laws would expand upon. These expectations included: state support, evaluation and accountability of educational efforts, and accessibility to an education that was "appropriate" to the disability.
Source: USDE, www2.ed.gov