Legal Question in Business Law in Washington

Re: Returned product

I'm assuming that you are in Wisconsin and your customer is in Washington. The following applies Washington law, as I assume that is where he would bring an action against you, if he decided to do so. (It's also the only place I'm licensed to practice.)

Your customer's rights are dictated by the contract between you, to start. You may not have a piece of paper that you both signed, but you should check the wording in your ads, in your communications to each other before the sale (including spoken), if any, or on the website, if you sold through a website (either your own, or someone else's, such as Ebay.)

If your communications and so forth are silent on the subject, then the "default" law applies. He must notify you of intent to reject the shipment as soon as he is aware of the problem, and he should follow your instructions for return from that point. He cannot notify you after he has taken opportunity to alter the shipment.