What is strangulation?
2.1Strangulation is the interference with blood or airflow by external pressure to the neck, leading to asphyxia (lack of oxygen supply to the body). The clinical sequence of a victim’s experience of strangulation may begin with difficulty breathing, dizziness and severe pain, followed by loss of consciousness. A victim described being strangled in this way:
I’m taking the pain, and I’m biting; I bit up my lips so hard I bit the whole [lip], all this is, this is gone, gone that’s how bad [I bit it]. [My daughter] didn’t know. She was there … it was like his whole finger is, like went up in there, and you can feel the imprint of his nails … and I can feel the bleeding, dripping, and you can just feel just feel it, and like, all right, this is my death warrant right here, and you cannot, you can’t talk.
2.2Three to five kilograms of pressure—roughly that recommended for very light polishing of a motor vehicle—applied to the neck for as little as 10 seconds can cause unconsciousness. A person will regain consciousness if pressure is released, but brain death can occur within four to five minutes if strangulation persists. There is, therefore, a fine line between fatal and non-fatal strangulation. The Family Violence Death Review Committee (FVDRC) observes that the danger inherent in strangulation “can be appreciated when it is understood that the brain needs a continuous supply of oxygen”. Without that, brain cells—which are not regenerative—malfunction and die.
2.3If a person is strangled to the point of unconsciousness, they may lose temporary control of their bladder and bowel and, afterwards, suffer cognitive changes like amnesia, confusion and agitation. These effects can go hand in hand so that a victim is left with evidence of an assault but cannot recall it. One of the groups we have consulted with described a victim who had passed out during a strangulation assault and lost bladder control but, when Police arrived, did not remember how that had happened.
2.4Strangulation is commonly described as “choking” or “throttling”. It can be distinguished from suffocation, which involves interference with a person’s ability to breathe but not necessarily by application of force to the neck.
2.5Usually, strangulation is performed “manually”—with the hands—but it can also be performed with a ligature (like a rope), by hanging or “posturally”, where the neck is put over an object and pressure applied. United States researchers who studied several hundred cases found that the vast majority involved manual strangulation, with victims describing being strangled with hands, an arm or by way of a choke hold.
2.6The relative ease with which a person can strangle another is due to the anatomy of the neck. The larynx is made up of cartilage (not bone), and the neck accommodates the carotid arteries (which are at the side of the neck and carry oxygenated blood from the heart and lungs to the brain) and the jugular veins (which carry deoxygenated blood from the brain back to the heart). A strangled person may lose consciousness because the carotid arteries are blocked (and so the brain is deprived of oxygen) or the jugular veins are blocked (and so deoxygenated blood cannot leave the brain) or the airway is blocked (so the person cannot breathe).
Signs and symptoms of strangulationTop
2.7Whether or not a victim loses consciousness, strangulation can cause what has been described as a “uniquely wide” range of adverse effects. During an assault, a victim may feel her legs go weak and her eyes “pop”, and afterwards may experience various symptoms and signs. Many tell-tale signs and symptoms are subtle, latent or delayed. This poses problems for medical and law enforcement personnel, as we discuss below.
2.8The symptoms of strangulation include:
- breathing changes and shortness of breath;
- difficulty with swallowing or a “thick” feeling in the throat, and neck and throat pain;
- nausea or vomiting;
- cognitive changes; and
- tinnitus (ringing in the ears).
2.9The signs of strangulation may include:
- bruising or abrasions to the neck, clavicle or jaw line, which may include ligature marks (if the abuser used a rope or other ligature);
- scratch marks on the neck (“defensive” wounds from the victim trying to ward off the attack);
- “petechiae”, which are small spots caused by blood leaking from capillaries;
- subconjunctival haemorrhage, which occurs when a tiny blood vessel breaks beneath the clear surface of the eye, resulting in a red mark; and
- hypoxic brain injury, caused when the brain’s oxygen supply drops, which can result in confusion, amnesia, restlessness and sometimes permanent disability.
2.10Petechiae tend to appear a few hours after an assault, whereas bruising can take several days to materialise. Some of the most serious effects, while extremely rare, may arise after a victim has apparently recovered. Examples include the following:
- “Thyroid storm”, which is a life-threatening rush of thyroid hormones, may arise days after a strangulation assault.
- There have been reports of victims suffering miscarriages or strokes caused by the strangulation.
- Some victims have died, several weeks after an attack, from brain damage caused by lack of oxygen during the strangulation.
2.11Strangulation also has a predictably serious effect on victims’ psychological and emotional wellbeing. Many report that, during an assault, they believed they would die, and the long-term impact can be sufficiently devastating that victims commit suicide.
Strangulation and family violenceTop
2.12Family violence incidents are often very complex. There may be no third-party witnesses, participants may be intoxicated and there may be allegations of violence from more than one party. Indeed, some victims of family violence and abuse use violence themselves, but that is not to say that the violence in such circumstances is mutual or equal. The FVDRC concluded, from its regional reviews, that:
… some abused women retaliate and resist coercive control by using violence themselves. This can include engaging in violence to try and establish a semblance of parity in the relationship, violent self-defence, violent retaliation and violent resistance. Primary victims may also use violence when they sense another attack from the predominant aggressor is about to occur.
2.13In these circumstances, the FVDRC cautions, a “primary victim/predominant aggressor analysis” is essential. In an abusive relationship, the “primary victim” is the person who (in the abuse history of the relationship) is experiencing ongoing coercive and controlling behaviours from their intimate partner, while the “predominant aggressor” is the person who is the most significant or principal aggressor in a relationship and who has a pattern of using violence to exercise coercive control. The FVDRC identified a lack of understanding of these dynamics in the New Zealand social sector and said it is important they are appreciated by those working in the criminal justice system.
2.14Unlike some other forms of violence—like hitting—strangulation seems to be the preserve of predominant aggressors. In the context of family violence, it has been described as a heavily “gendered” form of abuse between intimate partners. In the 29 strangulation assaults the FVDRC examined, a woman was the victim in 27 cases and a child in two, while in all cases, the aggressor was male. This is consistent with overseas research, which suggests that, over the course of a lifetime, women are between four and 11 times more likely than men to report strangulation by an intimate partner.
2.15Most of the literature is concerned with heterosexual relationships. Strangulation has been found to feature in same-sex relationships, but there is limited data on it. Intimate partner violence (IPV) in same-sex relationships has generally received much less attention than heterosexual IPV despite the fact it may be as prevalent or more prevalent. The FVDRC acknowledged that same-sex family violence deaths are likely to be undercounted.
2.16It has been said that abusers do not strangle to kill but to show that they can kill. In the context of IPV, it is arguably this element of strangulation that makes it a unique tool of coercion and control, apt to traumatise its victims long after the assault has ended. Perhaps unsurprisingly, strangulation is often accompanied by threats to kill.
2.17Strangulation is not confined to IPV. It features in “stranger” sexual assaults, and victims in the family setting include children and others as well as intimate partners. In this broader context, offenders are not always male or intimately associated with the victim. However, strangulation is strongly correlated with other forms of IPV, and women who have previously suffered other abuse are much more likely to be strangled. The FVDRC noted a “striking” coincidence of strangulation histories with the family violence deaths it reviewed.
2.18In the 1990s, San Diego Assistant City Attorney Gael Strack, physician George McClane and forensic pathologist Dean Hawley MD directed attention to strangulation as a form of IPV and, in 2001, published a review of 300 San Diego strangulation cases (the San Diego study). This study has been described as ground-breaking and pivotal and has been followed, in the United States and elsewhere, by a body of further research, policy and academic review, and law reform. The study’s main findings, substantially borne out in subsequent literature, were as follows:
- Most strangulation cases produce minor or no visible injury, but many victims suffer internal injuries and have documentable symptoms.
- Strangulation is a gendered crime. In 299 of the 300 cases the researchers reviewed, the perpetrator was male.
- Most abusers do not strangle to kill but to demonstrate they can kill.
- Strangulation victims often suffer major long-term emotional and physical effects.
- Victims of prior strangulation are more likely to become homicide victims.
Prevalence of strangulation in family violence
2.19New Zealand Police estimate that only 18–25 per cent of all family violence cases are reported, and the position is similar elsewhere. United Nations Women records that cases of violence against women “more often than not” go unreported, and a recent survey across 28 member states of the European Union revealed that only 14 per cent of women reported their most serious incident of intimate partner violence to Police.
2.20Strangulation may be particularly under-reported. Of the 29 strangulation assaults the FVDRC reviewed, the strangulation act was reported to Police in 16 cases and unreported in 13 cases. Morag McClean RN, a Canadian nurse who has written a guide for front-line workers and crisis advocates dealing with strangulation, cautions:
Victims often do not understand the lethality of strangulation and for many reasons will minimize the event or fail to report. For some victims, choking is considered to be a form of physical violence and therefore it is normal to be choked.
2.21Currently, strangulation in family violence cases is not systematically recorded. When it is encountered by Police in a call-out, it will be documented on the record, but various words and phrases will be used, including “choking”, “throttling” and “squeezing the neck”. This makes it very difficult to do an electronic search of the records to determine the prevalence of strangulation.
2.22Despite that, Police and women’s refuges report to us that it is very common in family violence. Women’s Refuge reports that the vast majority of victims it deals with have been strangled by their partners. The FVDRC found strangulation histories in 71 per cent of their regional review cases, and 50 per cent of those cases involved multiple strangulations. This led the FVDRC to conclude that strangulation is a clear “modus operandi” for some abusers.
2.23Overseas research includes comparable data. A 2008 study by a group of US medical researchers into several hundred attempted and completed intimate-partner homicides found a history of strangulation in almost half the cases. Among victims of “systematic” intimate partner abuse, just over 50 per cent reported having been strangled.
2.24Coercion and control is a major factor in many violent intimate relationships. It may be distinguished from “situational violence”, which is intermittent, not rooted in a desire to control and does not escalate over time. Unlike situational violence, IPV is characterised by coercion and control and involves an ongoing pattern of behaviours that cause a range of harms in addition to physical injury.
2.25To the extent IPV involves coercion and control, strangulation is arguably unique. It has been described as a “way an abusive partner can ‘set the stage’ by sending the message that he can, and perhaps will, kill the victim—a credible threat that is intended to induce compliance”. Thomas and others opine that strangulation “induces behavioural and emotional reactions that facilitate coercive control” through the “combination of fear and the inability to effectively resist”. In this way, strangulation might align more closely with sexual assault or torture than assault and battery crimes. Sorensen suggests:
Non-fatal strangulation might well be the domestic violence equivalent of water boarding … Both leave few marks immediately afterward, both can result in the loss of consciousness, both are used to assert dominance and authority over the life of the other, both create intense fear and potentially result in death, and both can be used repeatedly, often with impunity.
An indicator of future lethal attack
2.26A number of studies have examined the factors that make a victim of family violence at greater risk of a lethal attack. In 2000, the Chicago Women’s Health Risk Study identified risk factors for life-threatening injury or death in family violence circumstances by comparing longitudinal data on abused women against similar data on women who had been killed by (or who had killed) their intimate partner. While the conventional wisdom that past violence predicts future violence was borne out by the study, it also found evidence that, when the past violence involved strangulation or use of a weapon, the victims were at greater risk than when those factors were not present.
2.27A 2003 study comparing 220 victims of homicide by intimate partners to 343 victims of abuse sought to identify risk factors for homicide in abusive relationships. Its findings included that:
- strangulation, together with other factors such as stalking, forced sex and abuse during pregnancy, is associated with subsequent homicide;
- the strongest sociodemographic risk factor was lack of employment;
- access to firearms and use of illicit drugs (but not excessive use of alcohol) were individual characteristics of the abuser that were both strong risk factors for homicide; and
- being separated from the abuser after having lived with him was a strong relationship risk factor, as was having a child living in the home who was not the abuser’s biological child.
2.28A study in 2004 was designed to test the ability of the so-called “Danger Assessment” screening tool to predict intimate partner homicide. That tool lists 17 risk factors, one of which was “tried to choke (strangle) her”. The study found that strangulation carried a significantly increased risk of fatality (women who were murdered were 9.9 times more likely to have been strangled than women who were abused but not strangled) as did use or threatened use of a weapon (at 20.2 times the risk), threatening to kill (14.9 times the risk), being violently and constantly jealous (9.2 times the risk) and forcing the victim to have sex (7.6 times the risk).
2.29A key 2008 United States study found that women who were victims of strangulation were at a significantly increased risk of being killed or of an attempt to kill them. This study is often quoted to support separate offences of strangulation in other jurisdictions, so we will provide more detail. The researchers conducted interviews with three groups of people:
- relatives or close friends of 310 women who had been killed by their current or ex-intimate partner (the homicide group);
- 194 women who had been the victims of attempted homicide by a current or former intimate partner (the attempted homicide group); and
- 427 women who had been physically assaulted or threatened with a weapon by a current or former intimate partner (the abused group).
2.30The interviewees were asked questions to identify risk factors for homicide and attempted homicide using previously tested screening tools. The study found that women in the homicide and attempted homicide groups were far more likely to have a history of strangulation compared to the women in the abused group. Multivariate logistic regressions were conducted to estimate the odds of becoming a victim of homicide or of attempted homicide (versus a victim of abuse) if the victim had previously been strangled. They found that a person who had been strangled by their partner had a seven-fold increased chance of being killed in a later attack than a person who had been abused but not strangled, and a six-fold increased chance of being the victim of an attempted homicide attack.
2.31These studies from other jurisdictions provide strong evidence that strangulation is associated with an increased risk of a future fatal attack. It is important to note that an increased risk does not mean that a fatal attack will occur, merely that there is a greater chance that it will occur. However, the consequences are for the victim to die, so it is important that this increased risk is understood and taken into account by any person who is making decisions about the victim or the perpetrator of strangulation.