Hello. My name is XXXXX XXXXX I will be happy to answer your question.
I would suggest that you check with the instructor and also with Illinois Department of Motor Vehicles to see if this instructor is accredited.
Most accredited instructors work for accredited and licensed driving school.
The fact that the store had a conspicuous sign displayed that weapons would be checked and had to be unloaded, would constitute a sufficient notice to the public and because it is a private establishment, the store has every right to create and implement it's own rules (as long as they are not illegal) and implement/enforce them.
Generally if someone in a similar situation disobeys a reasonable request to either have the gun inspected as per posted store policy or to leave, but decides to disregard the request and goes in against the duly authorized employee's demand, the store employee did act within the law to call police and there would generally be no legal recourse against the store.
As far as having the charge "thrown out", it might be an uphill battle given the facts, but an experienced local criminal defense attorney might be able to work out a plea to a lesser violation or to dismiss the charge by claiming some sort of misunderstanding or question whether the notice of no loaded weapons was sufficient or conspicuously posted.
I know this is not an answer you were hoping to hear, but I am sure you would rather have a correct answer, than a more favorable incorrect one, that might give you false hope or potentially point you in the wrong direction.
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