Yiur question sounds more like a family civil dispute as opposed to a criminal matter since you refer that your son-in-law is taking you to court for discarding some items that he left at your premises when he moved out.The best defense that you would have to this civil action is that the material left behind was abandoned by him and despite attempts by you for him to come and get it, he never did so. Under many state laws, if the items left behind are less than $300 or so in value, the landlord/property owner can discard the property any way he or she seems fit.Good luck.