The Illinois State Police and/or arresting agency of the case may oppose your request if you don’t qualify for expungement or sealing under Illinois law. The State’s Attorney could also object for legal reasons (ex: not meeting Illinois law requirements) or for discretionary reasons. This means the State’s Attorney could object even if you qualify under the law.
Discretionary reasons might involve your previous arrests, the seriousness of the offense you want to clear, any violent crimes, protection orders, or if your sentence wasn’t completed satisfactorily.