"Drugged"? As in he was given a drug? If so, what type of drug was he given? How did you become aware of your son being given a drug?If he had so much trouble leading to the incident indeed an IEP would have been requested. He would have possibly not been drugged and thrown into a bathroom. He was 4 at the time and had not had a diagnosis or any behaviors constituting an IEP at the time this took place.
Or did you mean "dragged" and thrown into a bathroom?