The term proximate cause originated in civil law. In 1908, the legal definition of proximate cause was given in the Pawsey versus Scottish Union and Nation decision: “Proximate cause means the active, efficient motion that sets in motion a train of events, which brings about a result, without the intervention of any force started and working actively from a new and independent source.” Pawsey involved an insurance claim due to a fire in Kingston, Jamaica, following the 1907 Jamaican earthquake. The issue was whether the fire was the result of the earthquake which would have been an exclusion under the insurance policy. The case was appealed to the British Privy Council which agreed with the jury decision that there was reasonable doubt that the fire was started by the earthquake.6 Legally, it has been refined to the initial act that sets off a natural and continuous sequence of events that produces injury. In the absence of the initial act, which produces injury, no injury would have resulted (see also Palsgraf v. Long Island Railroad Co., 162 N.E. 99. N.Y. 1928). In malpractice claims, one element that a plaintiff must establish is that a breach of duty was the proximate cause of the injury. In 1948, the Sixth Decennial International Revision Conference agreed that vital statistics must code the underlying cause of death.5 They defined the underlying cause of death as: the disease or injury that initiated the train of morbid events leading directly to death or the circumstances of the accident or violence, which produced the vital injury. Their design of the new death certificate included separate entries for the cause, manner, and circumstances of death.7 From this similar terminology, it appears that the medicolegal definition of the proximate cause of death had its origin in the legal definition of proximate cause.
In law, a proximate cause is an event sufficiently related to a legally recognizable injury to be held the cause of that injury. The legal use of proximate cause mainly is concerned with torts and the assignment of negligence; however, there are logical similarities with the use of proximate cause of death by the medicolegal field. There are 2 types of causation in the law, cause-in-fact and proximate (or legal) cause. Cause-in-fact is determined by the “but-for” test: but for the action, the result would not have happened. For example, but for running the red light, the collision would not have occurred. For an act to cause harm, both tests must be met; proximate cause is a legal limitation on cause-in-fact. Since “but-for” causation is very easy to show and does not assign culpability (but for the snow, you would not have crashed your car), there is a second test used to determine whether 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 the proximate cause.
These tests of causality can be applied for death certification. The critical task in certifying a death following a remote injury is to determine whether the remote injury represents the proximate (underlying) cause of death. A prototypical example is a wheelchair-bound paraplegic (due to a remote gunshot wound of the spinal cord) who dies from sepsis due to infected decubitus ulcers. In this example, there are at least 3 injuries that meet the “but for” test—-gunshot wound, paraplegia, and decubitus ulcers—-but only the gunshot wound meets the proximate cause test. The search for the proximate cause ends with the determination of the etiologically specific disease or injury.
Delayed Homicides and Immediate Causes
An antiquated English common law rule holds that a death must occur within a “year and a day” after an assault to be considered a homicide. This rule has occasionally been invoked as a defense in jurisdictions where it had yet to be explicitly revoked (see State of Wisconsin v. Picotte, 2003 WI 42). A US Supreme Court ruling in July 2001 affirmed a State Court's abolishment of the rule (Rogers v. Tennessee, US 99–6218) stating that “advances in medical and related science have so undermined the rule's usefulness as to render it without question obsolete.” It also was abolished in Great Britain with the Law Reform Act of 1996. The gradual extinction of the “year and a day rule” for bringing homicide charges in delayed deaths, may result in more of these deaths proceeding to trial. Medical examiners/coroners must be prepared to explain the reasoning behind these death certifications and maintain consistent standards for the certification of all delayed deaths due to any injury (homicides, suicides, and accidents).
Medical examiner/coroners have no time limit for the interval between an injury and death to invoke the injury as the proximate cause. Therefore, the potentially long interval that may occur between a traumatic injury and death can complicate the cause of death determination. Common problems include the failure of care providers to recognize and report deaths due to remote traumatic injuries, the difficulty in sorting out a complex sequence of events interposed between the injury and death, and the lack of adequate documentation of the original injury and its circumstances. This application of the proximate injury in delayed deaths is not only applied to homicides. Delayed deaths due to injuries regardless of the circumstances (accidents, suicides) also are certified with this method.
It is important to note that a medical examiner/coroner's determination of homicide as a manner of death is not equivalent to a determination of homicide by a judge or jury. Certification of the manner of death by a medical examiner/coroner is primarily for vital health statistical purposes but also is used by insurance companies and other agencies for internal administrative purposes. The cause of death certification may be more important in subsequent legal proceedings because it requires the gathering of facts obtained through a medicolegal investigation, including an autopsy, and the specialized knowledge to interpret those facts. In criminal trials, the manner of death is ultimately a question for the jury to answer.
Nonetheless, the certification of a homicide requires a higher degree of certainty (ie, a reasonable degree of medical certainty) than natural deaths or accidents (a preponderance of the evidence).5 In deaths due to recent injury, it usually is not difficult to meet this higher standard since the mechanism of death (eg, exsanguination) is clearly linked to the injury. When trauma kills so quickly that there is no time for sequelae to develop, the injury is both the immediate and proximate cause of death.8 In delayed deaths, there typically is an interposing immediate cause. These immediate causes (bronchopneumonia, urosepsis) may result from natural diseases as well as consequences of injury. Therefore, in these delayed deaths, one must link the death to the immediate cause and link the immediate cause to the remote injury. Both links must be made to a reasonable degree of medical certainty to certify the death as a homicide. This higher standard may be difficult to meet in some instances of delayed death and typically requires a diligent review of available records and an autopsy (particularly if competing or contributing conditions unrelated to the remote injury are a concern).
The cause of death may be affected by the detection of other non–injury-related comorbidities. The incidence of life-threatening, cardiovascular disease increases with increasing age. In our series, 10 decedents were over 60 years of age and there were some deaths in which coexisting natural disease made a contribution to the death. The decision to include these contributing conditions depends upon a careful review of the circumstances and autopsy findings. The 3 questions that arise with concurrent natural disease are: (1) is the comorbidity to the extent that it is an efficient intervening cause of death? (2) Did the comorbidity contribute to the death in conjunction with the remote injury? (3) If so, was it a major or minor factor? Contrariwise, if the remote injury contributes at all to the death, then the injury will dominate the manner of death determination. For example, one delayed homicide was certified as cardiac arrest due to hypertensive disease (in part 1). This death occurred during emergent surgery for an incarcerated incisional hernia due to a remote repair of a stab wound, which was listed as a contributing condition (part 2). The manner was certified as homicide.
There is a potential for obfuscation or confusion with the immediate cause. Particularly in legal proceedings, a party may attempt to blame the death on the immediate cause, ignore the proximate cause of death, or focus on comorbidities. In some instances, there may be an attempt to shift the blame to the caretakers who did not “adequately” care for the patient. These diversions usually can be addressed by the simple fact that this person would not have died at this time from this complication if the original injury had not occurred. The patient would not have required an indwelling urinary catheter or developed a decubitus ulcer if there was no initial injury. It has been said that the constitution does not guarantee an assailant the right to a healthy victim nor to a doctor who knows how to fix a broken leg. As Adelson noted: “If a wound not necessarily fatal, leads to the development of septic or other complications which terminate fatally, the person causing such a wound is responsible for the death as though the wound he inflicted were necessarily fatal. Nor will the fact that the victim might have recovered had a neglected wound been properly treated relieve an assailant of responsibility for causing the death if the original injury was feloniously inflicted.”8 Contrariwise, if a “wound is not mortal and death results from an independent cause,” then this is an example of an efficient intervening cause and the death would not be certified as homicide.8
The morbidity and mortality associated with both paraplegia and quadriplegia are well described in the medical literature.9,10 Studies on paraplegics and quadriplegics have demonstrated long-term survival. A study of nonventilator-dependent patients who survived a traumatic spinal cord injury (without concurrent moderate or severe brain injury) incurred between 25 and 34 years of age in Ontario, had a median survival of 38 years postinjury.10 They also found a difference in the median survival time for paraplegics and quadriplegics (41 vs. 32 years postinjury). Factors that affect mortality include age at the time of injury and year of injury. Injury at younger ages experience better survival outcomes and, due to treatment improvements, injuries that occurred after the early 1970s also have a decreased mortality. There have been conflicting data on whether the vertebral level of injury predicts mortality.10 A study in Great Britain examined long-term survival in over 3000 individuals with spinal cord injuries that occurred over a 50-year period.9 They found the top 3 “causes” of death were: pulmonary infection, urinary system complications, and heart disease. Men were 75% more likely than women to die of urinary system disease. Our data show a high number of infection deaths in the patients with paralysis. Decreased ambulation affects many aspects of the body including the cardiopulmonary system (deconditioning11), skin integrity, and genitourinary dysfunction with the chronic need for bladder catheterization. Infections due to chronic bladder catheterization are a well-described complication in patients with spinal cord injuries.12–15
Posttraumatic seizures are a well recognized complication of brain injury.16–19 Posttraumatic seizures are categorized as early (within one week of the injury) and late (after 1 week). Annegers et al studied over 4500 children and adults with traumatic brain injury.16 They found significant risk factors for later seizures included brain contusion with subdural hematoma, skull fracture, loss of consciousness or amnesia for more than 1 day, and an age of 65 years or older. Seizures following penetrating war injuries also have been reported.19 The risk of posttraumatic seizures after severe head injury is 7.1% within the first year and 11.5% within 5 years.18 Approximately 5.5% of all patients with a diagnosis of epilepsy have a history of head trauma and the incidence of having at least one late seizure in patients treated for a head injury is about 2%.17,18 The risk of developing posttraumatic seizures extends for years following the injury with approximately 50% occurring within the first year after the injury.19
In summary, this is a series of 42 delayed homicides over a 2-year period in a large metropolitan medical examiner jurisdiction. To our knowledge, a previous series of delayed homicides has not been reported. Common scenarios of delayed homicides include: infected decubitus ulcers, bronchopneumonia, and urosepsis due to paralysis following gunshot wounds of the spinal cord; seizures following blunt head injuries; and small bowel incarceration/hernia following stab wounds. In making consistent and accurate cause of death determinations in delayed homicides, it is important to rely upon the definition of proximate cause of death.
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Keywords:© 2009 Lippincott Williams & Wilkins, Inc.
forensic pathology; homicide; proximate cause; delayed complications