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Science, liability, use of force, and restraint asphyxia

Research shows that a sudden in-custody restraint death is a statically rare event given the annual number of police contacts with citizens

Adversaries involved in civil lawsuits and criminal legal actions often call on scientific study to support their arguments — this practice has been part of the American legal system since the 1800s. But there’s a tension between law and science, principally because their respective objectives are different. Sometimes though, science and liability intersect and this is particularly true in cases of sudden restraint deaths in police custody.

These cases tend to involve complex medical, legal, and use-of-force issues. These incidents typically involve a violent confrontation between an individual the police. Often times the civilian person is exhibiting a drug-induced state of agitation, or agitation commonly found in a mentally ill person. The violent encounter generally requires several officers to employ less-lethal force techniques and equipment in order to ground, control, and restrain the person. The person may be restrained with only handcuffs, or leg restraints, or their combination. The once-combative person becomes tranquil, unresponsive, requiring medical intervention. Efforts to revive the person by officers or medical personnel are unsuccessful, whereupon it is determined that the individual is dead — all within a short amount of time after restraint.

Autopsy findings may fail to show anatomic or toxicological results sufficient to explain the death. Classifying the manner of death in a sudden restraint death can be problematic for the pathologist as he or she must determine whether evidence supports a natural death, homicide, accident, suicide, or is undetermined. Once a classification of the manner death is determined closure of the incident is hardly over, as a civil lawsuit will most assuredly be filed against the restraining officers and agency command personnel for allegations of a wrongful death.

The tension between science, the use of force, and the law will emerge between the restraining officers, the estate and their legal counsel, and the pathologist. Regardless of the force techniques and less-lethal equipment used by law enforcement to control the subject, the nature of the inquiry into the cause of death generally focuses on whether the officers’ restraint procedures contributed to the decedent’s death. Medical experts from the plaintiff’s perspective will examine the physiological science of using restraints on combative subjects to support a hypothesis that such procedures contributed to the death of the decedent regardless of the cause and manner of death. Generally, these medical experts will attempt to prove that the cause of death resulted from a theory of “positional or restraint asphyxia” as a result of prone restraint. The claim is that placing the subject in the prone position for control and restraint and/or the weight applied to the back of the subject during restraint interfered with the mechanics of ventilation, causing asphyxia, and death.

Conversely, medical experts from the defendant officers’ perspective will also analyze the physiological science of restraint of a combative person to determine if the restraint procedure or other medical conditions were more likely to have contributed to the death. Counsel for either party will also request police experts to examine the reasonableness of the officers’ use of force techniques and equipment when faced with such a violent resistance confrontation.

Both perspectives underscore the tension between science and the law that intersects from a sudden in custody death. Each perspective will analyze the use of restraint procedures used by the police and attempt to use the science to argue and support their respective position. Hence the few physiological scientific studies that exist on this subject are paramount in assisting the legal parties in assessing any potential culpability.

Due to the controversial nature of a sudden in custody restraint death, numerous case and retrospective studies, incident reports, and monographs have been published since the 1980s in order to bring awareness of the subject matter. While these studies have assisted in heightening the awareness on the topic, they do not provide scientific evidence of the cause of death. Only nine experimental scientific studies have been conducted on the subject in an effort to explain the cause of a sudden restraint custodial death. Consequently, a systematic analysis of these studies was performed to evaluate their findings. This analysis is presented so that law enforcement officers may have a greater understanding of how to apply the science to incidents of use of force in sudden in custody restraint deaths.

Research shows that a sudden in-custody restraint death is a statically rare event given the annual number of police contacts with citizens. Researchers of the Department of Justice (DOJ) report that from 1996 to 2004 police contact on average about 45 million citizens age 16 or older annually (Greenfeld et al. 1997; Langan et al., 1999; and Durose, et al., 2005). Of these contacts about 550,000 resulted in a use of force or threatened use of force situation. Mumola (2007) of the DOJ also reported that restraint deaths accounted for about 75 deaths during from 2003 to 2005. Using the annual average of 550,000 use-of-force situations and the reported approximate number of annual restraint deaths of 25, it is estimated that a sudden restraint in custody death has about a .000005 percent likelihood of occurrence.

While a sudden restraint death in police custody is rare, one death can create a complex investigation and a lengthy civil litigation process. Therefore, the findings of this analysis will benefit the police in better understanding of the nature of controlling and restraining a violent subject in the prone position.

Research Methods
Using a content analysis, databases of Medline and ProMed published studies on the subject of a sudden death in police custody during a violent confrontation and restraint were assessed from 1985 through 2008. A total of 75 publications addressing sudden deaths in police or detention custody in which restraint of the person (positional asphyxia) was the primary issue assessed were reviewed. These articles were separated into the following classifications: case and incident studies (n=40); retrospective case studies from incidents and autopsy reports (n=21); monographs and technical reports (5); and physiological scientific experiments (n=9). Studies which only addressed excited delirium deaths from substance abuse or deaths from agitation of the mentally impaired without referencing restraint procedures used by the police were excluded.

The research protocols of each study were examined by using the four criteria established by the United States Supreme Court’s decision in Daubert v. Merrell Dow Pharmaceutical, Inc. (1993) along with the following criteria: (1) methods and protocols employed; (2) statistical analysis applied, (3) number and gender of subjects used; (4) limitations of the research, and (5) the findings and conclusions presented.

Further, an assessment of the prevailing trends of 254 published Title 42 U.S.C. §1983 civil liable cases which were litigated on sudden deaths in custody was performed. Case decisions from the LexisNexis data base were examined from 1983 to 2009. A synopsis of the prevailing patterns of these case decisions is useful in illustrating how the courts apply the published scientific research to allegations of a wrongful sudden in custody death resulting from a restraint incident.

Highlights of the findings of this study are reported in two parts: Part I presents findings of the experimental research on restraint asphyxia and Part II reports on the findings of the §1983 litigation trends and provides recommendations for policy and training. The findings can assist agencies in being better prepared to defend against wrongful death legal allegations (the entire study can be reviewed in the Law Enforcement Executive Forum Journal; March, 2010).

Findings of the Physiological Experimental Studies
Nine published scientific experiments on restraint asphyxia were assessed, and two were conducted in the UK. Of these studies, five researched hogtying and positional asphyxia; 1 study examined responses of subjects exposed to pepper spray and being hogtied; and three studies examined weight force, restraint, and asphyxia. A total of 135 subjects participated in these studies and 98 were male. The average age was 31.

Of these research experiments the Reay et al. (1988) study can be classified as “flawed or junk science.” Reay et al. reported that after exercise and being placed prone in the hogtied position, the risk of positional asphyxia increased. However, as more sophisticated research by other researchers was conducted, Reay (1998) retracted his original conclusions on positional asphyxia acknowledging that hogtying is physiological neutral (see also Price v. County of San Diego, CA, 1998). The Roeggla et al. (1997) study methods were also flawed. The authors made conclusions about ventilatory changes in the restraint position that are not validated by the data presented. While the subjects were placed in a variety of positions exercise or struggle as a component was not designed into the experiment. Without the component exercise conclusions of the study cannot be supported regarding the effects on ventilation. They reported no significant effects to any cardiopulmonary parameters and the study demonstrated no ventilation compromise, hypoxemia or hypercapnia with the restraint position to suggest an increased risk of asphyxiation.

Further, the Krauskopf et al. (2008) study design had several flaws. The researchers also failed to exercise the subjects, or have the subjects struggle before or during the exercise. Moreover, the subjects lay unrestrained on a mattress with their arms draped out over the mattress in a normal fashion while weights were placed on their lower back for an unspecified period of time. The study findings did not demonstrate hypoxia or hyercapnia, and the researchers concluded that cardiovascular parameters were uninfluenced by weight force application.

Findings of the remaining experimental six studies contribute to clarifying the science behind restraint physiology (Chan et al. 1997; Schmidt and Snowden, 1999; Parkes, 2000; Chan et al, 2002; Chan et al. 2004; Michalewciz et al. 2007). Despite the obvious and apparent limitations associated with laboratory experiments with human subjects, these studies followed rigorous experimental methodological design, used randomization of respondents with trial applications, used appropriate statistical analysis and probability values, medically pre-screened participants, required subjects to exercise or struggle prior to restraint, and followed appropriate human subject research protocols.

The studies do not support the contention that ventilation is significantly comprised, regardless of being placed prone and restrained; being restrained hogtied or placed in a prone position, with or without weight on the back; or restrained, hogtied, and exposed to pepper spray. From a medical perspective, these studies reveal that there is no evidence that the hogtied position, in and of itself plays a risk factor for asphyxia. Collectively, the studies conclude that the prone restraint position, nor the hogtied restrained position, with or without weight force, contributed to abnormal pulmonary function, hypoxemia (deficient oxygenation of the blood), hypoventilation (decreased lung ventilation), or hypercapnia (excessive amounts of carbon dioxide in the blood) sufficient to cause asphyxia. Moreover, the findings are supported by prior work on exercise physiology which indicates that arterial oxygenation improves rather than decreases with moderate exercise in healthy people (Levitzy, 1995; Wasserman, et al. 1994).

The physiological science of restraint not only clarifies that the restraint position or restraint procedures fail to support a sudden death from ventilatory compromise but also reveal that other more significant factors are more likely to contribute to a sudden violent restraint death. Other factors such as excited delirium, drug intoxication, mental illness, stress, trauma, and catecholamine hyperstimulation, are considered to be factors playing the most significant role in these sudden deaths (Ross, 1998; Ruttenber, et al., 1997; Wetli, 2006, 2005; Laposata, 1993; Karch, 2008; DiMaio and DiMaio, 2006). Moreover, other studies show that a significant number of individuals who suddenly die after restraint have an abnormally enlarged heart, linked to chronic drug abuse, and have internal organ deficiencies (Herd, 1991; Karch, 2008; Karch and Green, 1995; Karch and Stevens, 1999; Laposata, 1991, 2006).

The basic tenets of exercise physiology support the conclusions of the six published scientific experiments. Appling the fundamental tenets of exercise physiology Glatter and Karch (2004) and DiMaio and DiMaio (2006) conclude that merely restraining an agitated person cannot possibly lead to significant hypoxia unless, there is some preexisting problems with central cardiac output, peripheral oxygen extraction, or oxygen utilization. They concluded that positional asphyxia in and of itself cannot cause this outcome and there is no evidence that physical activity causes life threatening episodes of hypoxia, no matter how strenuous the activity.


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Case Citations
Daubert v. Merrell Dow Pharmaceutical, Inc. 509 U.S. 579 (1993)
Price v. County of San Diego, 990 F. Supp. 1230 (S.D. Cal. 1998)

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