The District/School has more responsibilities when it comes to dealing with the bullying of a Special Needs child. The US Dept of Education has published several Dear Colleague letters about it, and indeed the Office of Civil Rights (OCR) has also published their guidance.
https://www2.ed.gov/about/offices/list/ ... sue08.html
One of the first things that needs to be done if your child says they are being bullied, is to notify the school the proper way. There is what is called a Gebser letter. The Gebser letter got its name from a Supreme Court case back in 1998 where one of the justices wrote that you cannot sue a District for bullying/harassment unless you have first notified the school of the bullying/harassment taking place. This letter ensures that the District/School was notified correctly. That takes care of the notification part, and lets the District/School know in no uncertain terms that they need to investigate and take proper action. A sample Gebser letter can be found here https://mustangps.net/downloads/Sample- ... Letter.pdf
Now simply notifying the school the proper way is not enough to win a lawsuit. There are other factors. Hopefully however, the receipt of the Gebser letter will ensure that they take the bullying seriously and take steps to stop it so that no further action on your part is needed.