Determine if you have standing. Standing is a legal interest someone has in a controversy, allowing him to sue another in court to resolve the dispute. If you have an interest in trust property, you have standing with regard to the trustee’s actions relating to the trust. People with an interest include current beneficiaries as well as people who may become beneficiaries in the future.
Evaluate the grounds of the suit. A trustee owes a fiduciary duty to the beneficiaries and is required to carry out the trust as defined by the terms of the trust agreement. This fiduciary duty compels the trustee to manage the trust for the sole benefit of it's beneficiaries. The trustee is prohibited from taking any action that would benefit him while managing the trust property. If the trustee has failed to meet any of these obligations, you may have grounds to sue.
Prepare all appropriate legal documents and file them with the clerk of court. The first document you need to prepare is a complaint, which should list how the trustee failed to meet his responsibilities, and ask the court to take action to compensate you for the trustee's actions. The summons is a written notice that you will send to the trustee informing him of the lawsuit. The court clerk keeps track of all filed legal documents. The clerk will assign a court date for your hearing, stamp all documents with your case number, and keep a copy for the court. Prepare multiple copies of all documents for your records.
Notify the co-trustee of the suit. All summons in Illinois must be delivered either by law enforcement or certified mail. This is to ensure the defendant is notified of the case. You should receive a document from the sheriff or postal service confirming the summons has been delivered.