New Zealand’s approach to women’s ‘insanity’ is archaic

The defences of infanticide and insanity have been front and centre for the past month in the trial of Lauren Dickason, the mother accused of smothering her three young children. The case is troubling in part because Dickason appears to have been a loving, involved, and attentive mother until she killed her children. Her act of filicide was her first act of child abuse.

The Crown’s case was that Dickason killed her children as an act of deliberation, anger, and revenge. Dickason mounted the outdated and problematic 'infanticide' defence, along with a more traditional insanity defence.

Dickason offered evidence that she suffered from a long history of depression and anxiety, which worsened to include psychotic symptoms after the birth of her eldest child. She struggled with fertility issues, a miscarriage, the pandemic, lockdowns, managed isolation, and moving to Aotearoa New Zealand from her native South Africa while parenting three small children. In 2019, she confided in the girls’ father that she was horrified because she was having thoughts of hurting the children. He chalked it up to her depression and told her to pull it together. In 2021, Dickason discontinued her anti-depressant medication, and her depression worsened. She confided in both a psychiatrist and a friend that she was suicidal. She cried frequently and lost a lot of weight. After killing her children, Dickason tried to kill herself. Her plan was to meet them in heaven.

Dickason’s internationally-renowned expert psychiatrist offered evidence that Dickason’s mind was “disturbed by a disorder that was a consequence of childbirth” and that the killings were related to her mental health struggles surrounding her miscarriage, postpartum depression, and parenting. This is because the 'infanticide' provision of the Crimes Act creates a partial defence for women who cause the death of their children under the age of 10 if they are “mentally disturbed” because of childbirth or lactation.

This crime of infanticide carries a far lesser sentence than homicide. In effect, it functions as a half-insanity defence, a legally-authorised act of compassion for filicidal mothers.

The infanticide law does not require that the woman was suffering from a recognised medical condition, only that her “mind was disturbed”. The defence only applies to women, and there is no requirement that the mental disturbance caused the killing. While infanticide defences are usually supported by expert evidence, ultimately, the determination of whether a mental disturbance partially excuses the homicide is up to the subjective moral intuition of the jury.

Partially excusing 'disturbed' women who kill their children has a troubling history. The infanticide construct arose from cultural beliefs that there was something different about struggling new mothers who killed their children, which warranted leniency. It also arose during a time when Aotearoa New Zealand had a mandatory death penalty for murder, a penalty that has long been abolished for all offenders and offences. Public sympathies toward women who killed their children during periods of stress or socio-economic deprivation led them to refuse to convict women of murder, delegitimising the jury function in the eyes of many. The infanticide defence was created to give juries a legal outlet for those sympathies. It was easier to compromise and treat maternal filicide as a lesser offence than to confront the structural and socio-economic factors that lay beneath some of these crimes.

The partial defence was based on early 20th Century pseudo-science and gender stereotypes, not to mention the broad upper-class Pākehā opposition to breastfeeding at the time. Medical researchers have subsequently disproved the myth that lactation causes mental illness. While postpartum depression and, rarely, postpartum psychosis are real psychiatric phenomena, the infanticide defence turns these conditions into stereotypes and generalises them to all mothers. What we are left with is a law that disingenuously links childbirth and lactation to a vague and ill-defined “mental disturbance”.

We have kept this infanticide construct largely to fill gaps in our insanity defence, which is narrow and also outdated. The insanity defence excuses people who commit crimes because they have a “disease of the mind” that renders them incapable of understanding the nature and quality of their actions or knowing that they were wrong. The threshold for the insanity defence is high – the defendant must essentially be totally mentally incapacitated by mental illness. Very few mental illnesses result in this total incapacity. Even severe depression and anxiety will almost never meet this threshold.

The result is that insanity is an all-or-nothing proposition. A defendant who commits crimes due to serious mental illness is either deemed completely incapacitated and therefore without any legal responsibility for their criminal conduct or they are deemed just barely competent and held fully responsible. Our criminal law does not generally recognise the concept of 'diminished responsibility' due to diminished capacity – the idea that some offenders should be held partially responsible if they offend due to a serious mental illness that does not render them cognitively incapacitated.

Other countries (eg Scotland and parts of the United States) recognise the concept of diminished responsibility – the idea that responsibility functions more like a sliding scale and that there ought to be a form of partial responsibility for people who commit serious crimes due to the effects of serious emotional disturbance. This is precisely what the infanticide defence does, but only for women, only if their capacity is diminished by childbirth or lactation, and only if they kill their children.

Today, this infanticide compromise has led to an inconsistent and unprincipled approach to filicide. The law feeds into societal misconceptions about how physiological aspects of womanhood (childbirth, breastfeeding, PMS, menopause) render women deranged and disturbed. It feeds into tropes that men who kill are 'bad' while women who kill are 'mad'. There is no science behind these stereotypes, which have been used to deny women positions of leadership and power. The infanticide compromise invites juries to act on their biases and prejudices by requiring them to make subjective moral judgments about whether mothers who kill are sympathetic, “evil”, or “disturbed”.

It is time for Aotearoa New Zealand to modernise its approach to insanity by recognising that mental illness can affect decision making in a host of ways. It should recognise that extreme emotional disturbances can occur in all people for a complex set of reasons that have nothing to do with motherhood, nursing, or female hysteria, and it should apply to any offender whose psychiatric disability precludes them from making fully capacitated decisions.