The police report is not the final decision on fault. In Illinois, what matters for your claim is whether the evidence shows you were less than 50% at fault. Under 735 ILCS 5/2-1116, you can still recover damages if you are 49% or less responsible, but your compensation is reduced by your percentage of fault. If you are 50% or more at fault, you recover nothing.

That matters a lot in Chicago on-ramp crashes, especially on short expressway merges like the Dan Ryan, Kennedy, Eisenhower, and Stevenson entrances, where cars are often forced to merge at 30 mph into 60 mph traffic. On holiday weekends like Memorial Day, July 4th, Labor Day, and Thanksgiving, insurers often argue the merging driver caused the crash. They also look for alcohol, speeding, distraction, and failure to yield.

To prove you can still recover, you need documentation showing what happened and what made your injuries worse:

• Crash report from the responding agency, usually Chicago Police Department or Illinois State Police
• Scene photos and video, including ramp length, lane markings, damage, skid marks, and traffic conditions
• Witness names and statements
• Dashcam or nearby camera footage, including IDOT traffic cameras if available
• Vehicle data, repair estimates, and black-box information when preserved
• Medical records before and after the crash, especially if you already had a back, neck, knee, or shoulder problem
• Doctor opinions stating the collision aggravated a pre-existing condition, not merely that you had one before
• Wage records if the worsened injury kept you from working

Insurance companies commonly ask for old scans to argue "this was already there." In Illinois, that does not defeat a claim if the crash aggravated, accelerated, or activated the condition. The key question is not whether you were previously injured. It is whether this crash made you measurably worse, and whether the other driver still carries more fault than you do.