刚发现IL也有这样的law "To determine liability for slips and falls on snow and ice, Illinois follows what is known as the unnatural accumulation of snow and ice rule. In order for there to be liability for a fall on ice or snow, the ice or snow that made you fall must be an unnatural accumulation of ice or snow. If it is a natural accumulation of ice or snow, there is no liability. " "the snow and ice is considered a natural accumulation if it is the result of natural weather conditions. This means that if the basis of your case is that the snow and/or ice was not shoveled or salted, there is no liability for the property owner."