Yesterday evening, a Southwest Airlines plane tried to land in bad weather at Midway Airport, but failed. It skidded past the runway, through a fence and into traffic on an adjacent road killing a six year old boy. In due time, it is almost certain that the boy's family will bring a wrongful death suit against the airline.
The success of that lawsuit will depend to a very great extent on whether a legal doctrine called res ipsa loquitur applies. More or less, what "res ipsa loquitur" means, is that the people who caused the harm won't be able to argue the "shit happens" defense.
While there are a host of different theories for holding someone responsible in a court of law for an accident, the vast majority of lawsuits arising from an accident are based on a legal theory called "negligence" mostly because the situations where other legal theories can be used are far less common.
In a negligence lawsuit, the injured person must prove: that the person sued had a duty to them, that their injury was caused by the person sued, that the person sued breached that duty, and the extent to which that person suffered injuries. These suits are called negligence lawsuits, because there is one duty which you owe to everyone even if you have no other relationship with them. This duty is the duty to act with reasonable care to avoid injuring other people and other people's property. A breach of this duty is called "negligence".
The classic negligence suit is the car accident. In a car accident, it is not enough to prove that someone else's car hit your car, you must also prove that it hit your car because the other driver was doing something wrong. For example, maybe the other driver was on his cell phone and not watching where he was going, or maybe the other driver ran a red light or went through a stop sign without looking.
The trouble is, that there are frequently cases where common sense tells you obviously that one person was more at fault than the other, even when it is hard to pin down exactly what someone did wrong.
Sometimes, the doctrine of res ipsa loquitur, or a related concept, strict liability, applies, and the injured person can recover. The example given in Wikipedia (see the link above) is someone who is injured when an elevator under the exclusive control of one company crashes to the ground. In a case like that, the court will usually rule that an accident like that doesn't usually happen unless the person in control of the elevator was negligent, that there was someone in exclusive control of the situation, and that the injured person can recover as long as he or she can prove that he or she did nothing to cause the fall. The more common application of the rule is to passengers on commercial airplanes that crash, where, again, the injured person or the family of the person killed need only prove that the passenger didn't contribute to the accident.
The legal fiction behind the doctrine of res ipsa loquitur is that someone almost certainly had to be legally negligent for this accident to happen, even if no one can prove it. But, this legal fiction isn't really true.
There are many times when the doctrine of res ipsa loquitur does not apply, even though the situation was under the someone's exclusive control. For example, consider a surgery situation. When a surgery goes awry during surgery (as opposed to during the recovery period), the patient is almost never at fault (typically the patient in unconscious), typically there is a surgeon who is the "captain of the ship" who is in exclusive control of the operating room and everyone in it, and in a very large percentage of cases, there is some specific action of the surgeon or someone under his direction and control that happened which should not have happened which caused the bad outcome.
But, surgery is hard. Even the very best surgeons routinely have bad outcomes that arise from the conduct of the surgery itself, and even more routinely, even the best surgeons carry out the surgery in ways that are not textbook perfect but do not actually end up causing a serious bad outcome. From a patient's point of view, it would seem fair to allow recovery under a doctrine like res ipsa loquitur, because it is often very hard to say precisely what was done wrong, but is very easy to tell that something went wrong. Of course, surgeons take a different view. They feel that they should not be held reasonsible for the kind of mistake that a reasonable surgeon might make at some point in their career. The true legal standard strikes middle ground between those positions. Not every surgerical imprecision or misstep gives rise to legal liability, even if it does harm. But, the surgeon is liable if the surgeon makes a mistake that a reasonable surgeon would generally not make in that surgery under the circumstances. The injured patient must prove, not only that a mistake was made, but that it was the sort of mistake that reasonable surgeons don't usually make. A surgeon who didn't bother to wash his hands before surgery is likely to be held liable. A surgeon who cut a little too deeply in the right general place is likely to avoid legal liability.
In cases where the surgeon makes a minor mistake that many reasonable surgeons make on a regular basis because surgery is so hard, which causes a signficiant adverse outcome, the courts tell the patient, "too bad, shit happens". (The concept is similar to the reluctance of the courts to grant relief to a person who is probably actually innocent, but was never the less mistakenly found guilty by a court in a case in which the police, prosecutors, defense attorneys, judge and jury did not act improperly in any way, and the witnesses did not intentionally say anything untrue).
Let's look again at our case of the boy injured by the airplane. If the doctrine of res ipsa loquitur is found not to apply, each individual involved in causing the accident may very well be able to show that he or she used the care normally exercised by a reasonable person under the circumstances. The pilot and air control tower may have been misinformed about the conditions on the runway, the pilot may have taken the correct, but insufficient, steps to stop the plane once it became clear that the runway was worse than expected, and may have directed the plane in a direction that caused minimal loss of life (note that everyone on the plane lived with only minor injuries). The person reporting the runway and weather situation may have given the same report that 90% of people in that line of work would have given in light of the information available to him or her, but the weather conditions on this particular day at that particular runway may never the less have been sufficiently freakish that the usual standards for gathering information weren't sufficient. Or, the problem could have been entirely different. For example, perhaps a mechanic, in the plane's last overhaul months ago, slightly miscalibrated some key instrument in the plane that is only really important in a bad weather landing and which no reasonable pilot could have discovered, and this sort of slight miscalibration happens often even when good mechanics are doing the work. It is not unlikely that there is no way that the family of the boy who was killed will ever be in a position to know, through their own efforts, the precise technical reason for this accident. And, if res ipsa loquitur does not apply, they will not be able to recover from anyone involved in causing that accident unless they can show the precise technical reason that the plane crashed and furthermore show that reasonable people would not have made the mistake that was actually made in this case.
Res ipsa loquitur is really an imposition of a duty to avoid all mistakes, without regard to the extent to which a reasonable person might make them, which is very close to the notion of strict liability for all injuries a person has caused. In the airline case, the reason that we tend to think that the airline, and not the driver of the car that was hit, is at fault, is that we think that the airline has more duties than to simply act with reasonable care to not hurt others, which is the universal standard of duty to others that everyone has. We also think that the airline has a separate duty to keep the airplanes in the airport, no matter what happens. The driver of the car was not doing anything wrong, and the airline breached this additional duty, regardless of how careful they were being not to breach it.
In the same vein, many people would argue that dog owners and parents, respectively, have a duty to keep their dogs and young children from intentionally or carelessly hurting other people and their property, no matter what, even if a reasonable dog owner or parent might supervise the dog or child in the same way that they did (and hence the parent or dog owner was not personally being negligent). This additional duty, beyond the universally applicable duty to be careful, would make legal responsibility in these case more closely match our moral intuition about fault.
What really separates our moral intuition about the case of the airplane crashing onto a road near the airport, or a person letting their kids or dogs get out of control, from the situation of the surgeon, is that in the former cases we think that there are additional duties beyond the universal duty of care that apply, and we see few downsides to not imposing that kind of duty, while in the case of the surgeon, we are unwilling to impose more than a reasonable care standard because this could have the institutional effect of preventing lots of worthwhile surgeries from taking place.
(Notably, the frequency of accidents doesn't necessarily mean that a fault regime is necessary. Workplace accidents happen all the time, but we have made a policy decision as a society to consider workplaces to be under the exclusive control of the employer and impose strict liability on employers for workplace injuries in exchange for a reduced standard of compensatory damages that employers must pay when accidents do happen, under the worker's compensation regime. Likewise, many states, including, until recently, Colorado, have taken the opposite approach to minor car accidents with "no fault" automobile insurance, in which no one can hold anyone else legally responsible for a minor car accident even when the other driver was clearly negligent).
Indeed, this broader view of the kinds of duties that give rise to fault is more or less the position taken in civil law countries, where the civil codes generally provide simply that people have a responsibility for compensating others who are injured as a result of their fault. This isn't quite a "no fault" regime, but it allows for a much wider conception of fault, rather than the false equivalence between one kind of fault, negligence, and fault in general, which tends to be made in the American legal system in accident cases.