It is a formal request to have your license suspension "rescinded." You have to state the reason(s) why the Court should throw out your suspension. I will attach a link to the Cook County form for this, but I would strongly advise you to retain and attorney to handle this for you. You stand very little chance of prevailing on your own, and you will likely do something in the process that you will come to regret.
Time is of the essence when it comes to filing this petition. You have 90 days from when you received notice of the suspension, which is generally the day you got arrested, to file. As Mr. Wallin stated, you would be wise to speak with an attorney to see if you have grounds to make this formal request.
Once arrested for DUI, you will face a mandatory suspension of your Illinois driver’s license for a minimum of six months to one year for a first offender and a minimum one to three years for multiple offenders. This suspension takes effect on the 46th day from the date your citation was issued. Obtaining an attorney prior to your first court date affords you the best opportunity to rescind the DUI suspension and fully restore your driving privileges, many times before the suspension even takes effect. If you want to try and overturn the mandatory suspension, you must file a Petition to Rescind within 90 days of getting the ticket. There are five basic grounds on which your suspension may be rescinded. In addition to the five grounds for rescission, the State only has a limited time in which to provide you a hearing upon receiving proper notification of your Petition to Rescind.An experienced attorney can consult with you and quickly assess the chances of successfully rescinding your suspension based on those grounds.