Although I do not practice law in the State of Minnesota, here are my initial impressions. First, who is threatening you? The bar or the police? If the police are threatening you, I suggest that you consult with and/or retain an attorney prior to taking any further action. If the bar is threatening you this sounds almost like extortion. It is unclear to me under what theory of liability a bar could require a patron to pay for a drink spilled on a cash register unless it was, of course, intentional. It seems as if contributory negligence as well as causation would be extremely large obstacles for any potential lawsuit, in addition to the fact that very few attorneys would be willing to take on a case where the maximum damage is $4,000.00. Moreover, I have a very hard time believing that the bar could establish that the cost of repairing the register is anywhere near $4,000.00, and that would presumably be the only damages that the bar would be entitled to upon winning what can be described as a very weak case at best. To be safe, you should consult with an attorney; however, based upon the facts that you have provided it sounds like the bar may be trying to take advantage of you.