One of the most well known cases regarding special education is Brown vs the Board of Education.The case at the time was dealing with civil rights for African Americans but because Brown won the win was for everyone who may be discriminated against. Check out this site for some more information. http://americanhistory.about.com/od/supremecourtcases/p/brown_v_board.htm.
This site also lists several other important cases in Special Education and I encourage you to take some time to check them out yourself.
This video talks about more in depth about specific court cases. One of these cases is Plessy vs. Ferguson. Again dealing with civil rights of African Americans this case would later be used to benefit students with disabilities to gain the education that they deserve.