UCLA School of Law

In negligence law, "unavoidable accident" is the risk that remains when an actor has used due care. The counterpart of unavoidable accident is "negligent harm." Negligence law makes parties immune for unavoidable accident even when they have used less than due care. Courts have developed a number of methods by which they "sort" accidents to unavoidable accident or to negligent harm, holding parties liable only for the latter. These sorting techniques are interesting in their own right and also provide a way of conceptualizing the relationship between specific negligence and res ipsa loquitur, which are two variants of the negligence rule. One judicial sorting technique reveals a paradox of negligence law. New safety technology often reduces the amount of unavoidable accident and simultaneously increases the expected number of "compliance errors," or routine negligent lapses, that actors will make. Paradoxically, an actor's use of new safety technology can make it more likely that a court will sort an accident to negligent harm as opposed to unavoidable accident. The article develops these theoretical ideas through a series of graphical illustrations analogous to those of traditional price theory.