i.   Accident causing injury would not have occurred unless someone was negligent Newing v. Cheatham- Plane crashed into mountain evidence proved negligence
ii.  Instrumentality causing injury was in D sole control Larson v. St. Francis Hotel- Chair thrown out of hotel wind was not in D’s control
iii.  Injurious condition was not due to any vol. action or contrib. on part of P.
Key: the more uncertainty there is to the cause = more likely RIL
Good example of Res Ipsa – Ybarra v. Spangard P. receives damage to shoulder during appendectomy