How liable is a school for bullying?

A few years back my brother and I came to a new school, in a new area. There, the first year, we were both shunned socially. Kind of expected. But then rumors about my brother started, and soon he was absolutely harassed. He was physically pushed and hit, kicked. On many occasions. In eighth grade a SENIOR football player beat him up on the bus everyday. He quickly fell into depression. I don't know much about law, but I understand that the school had a legal obligation to protect him because he had "special needs" and an IEP for a learning disability and being suicidal. We were both bullied, but I pulled through it, and his was a lot worse. Now, of course my family took this to the administration. Both the principal and the vice principal- the disciplinarian- were the head football coaches. My brothers bullies were the star football players. The bullies got off even after numerous reports and a great deal of witnesses. My brother, however, was scolded for being "annoying". Also, in middle school, when my brother was close to suicide because of the bullying his grades were the least of his priorities, naturally. One teacher said, in front of the class of thirty students, "Is this the only class you don't try in? It's not, because these (X, Y, Z) are your grades in these (A, B, C) classes". I also have an IEP for reasons that I would not like to disclose for identification purposes. That same teacher also said to me in front of the class, "It's no wonder you don't have any friends, especially when you (have this IEP)". We reported both of these incidents to our administration on two different occasions and nothing was done. What can we do? My family would love to see the school (administration, especially) really screwed over. They caused my brothers health problems, and my family to suffer.