If the parent/guardian and the school district cannot reach a decision through mediation, or if the parent/guardian prefers not to mediate, he/she can request a due process hearing. Here the parent/guardian and the school district present written evidence about the disputed issue and have witnesses testify before a hearing officer. If the parent/guardian does not agree with the outcome of the hearing they can appeal the decision all the way to state or federal court.
Usually disputed issues revolve around parts of the IEP that cannot be agree upon. If the school district has violated a legal rule, such as failing to hold an IEP meeting, conduct an evaluation, meet a time limit or implement the IEP, the parent/guardian must file a complaint. Each school district has its own complaint procedure.