same amount of property damage would have resulted from either fire. Both campers are equally liable for all damage. A famous case establishing this principle in the United States is Corey v. Havener. In the United States, the rule of Summers v. Tice holds that where two parties have acted negligently, but only one causes an injury to a third party, the burden shifts to the negligent parties to prove that they were not the cause of the injury. In that case, two hunters negligently fired their shotguns in the direction of their guide, and a pellet lodged in his eye. Because it was impossible to tell which hunter fired the shot that caused the injury, the court held both hunters liable. Market share evidence. Injury or illness is occasioned by a fungible product made by all the manufacturers joined in a lawsuit. The injury or illness is due to a design hazard, with each having been found to have sold the same type of product in a manner that made it unreasonably dangerous, there is inability to identify the specific manufacturer of the product or products that brought about the Plaintiff's injury or illness and there are enough manufacturers of the fungible product joined in the lawsuit, to represent a substantial share of the market. Any damages would then be divided according to the market share ratio. Since but-for causation is very easy to show and does not assign culpability (but for the rain, you would not have crashed your carthe rain is not morally or legally culpable but still constitutes a cause), there is a second test used to determine if an action is close enough to a harm in a "chain of events" to be a legally culpable cause of the harm. This test is called proximate cause, from the Latin proxima causa. Other factors There are several competing theories of proximate cause. Foreseeability The most common test of proximate cause under the American legal system is foreseeability. It determines if the harm resulting from an action could reasonably have been predicted. The test is used in most cases only in respect to the type of harm. It is foreseeable, for example, that throwing a baseball at someone could cause them a blunt-force injury. But proximate cause is still met if a thrown baseball misses the target and knocks a heavy object off a shelf behind them,