Res ipsa loquitur is one of those Latin phrases lawyers like to use.  It simply means the act speaks for itself.  So when an accident happens that causes injury or property damage that would only happen if someone was at fault, or negligent, then the burden of proof shifts to the defendant to prove that he/she was not negligent.  This burden shifting is important when there are multiple defendants who have the only knowledge about which one of them was actually negligent, or at fault, for causing an accident.  For example, a few years ago a group of young adults held a party in a barn in Goffstown, New Hampshire.  The barn burned down shortly after the party ended.  The State Fire Marshall was able to determine that the fire was caused by someone leaving a lit cigarette on an old couch.  The group of young adults were sued by the property owners, and the owners sought recovery based on res ipsa loquitur.  The trial court agreed to allow the theory to proceed, and the burden shifted to each defendant to prove they did not leave behind the lit cigarette or face joint liability for the loss of the barn.  The trial court issued two orders involving res ipsa loquitur and the application of burden shifting to multiple defendants. Order on Sumary Judgment (res ipsa); Order on Amended Writ (res ipsa).