Issues often arise between the school system and the parents concerning eligibility for special education services, the type of services that are legally required, and the environment in which services are going to be provided. Disputes also arise from time to time about whether an agreed upon individualized education program has actually been implemented by the system. When those disputes cannot be resolved at the local level, legal services are sometimes required.
You have the right under IDEA to request a hearing before the State Department of Education. This is called a "due process" hearing. A hearing officer will be appointed and he will resolve the issues between the parties. The hearing officers are not employees of the State Department of Education; they are administrative law judges who have a duty to make a fair and impartial decision under the law.
Because the due process hearing is a legal proceeding, it is best to have an attorney to represent you in this hearing. The hearing is somewhat like a trial--although there is only a judge and the hearings are somewhat more informal than traditional court proceedings. Nonetheless you should be represented by an attorney.