The Insanity Defence without Mental Illness

Today's post is by Marko Jurjako, Assistant Professor of Philosophy at University of Rijeka, regarding the recent paper ‘The insanity defence without mental illness? Some considerations’ that he co-authored with Gerben Meynen, professor of Forensic Psychiatry (Utrecht University) and endowed professor of Ethics and Psychiatry (VU University Amsterdam) and Luca Malatesti, Associate Professor of Philosophy at the University of Rijeka. Marko and Luca’s work on this paper is an outcome of the project Responding to antisocial personalities in a democratic society RAD, that is financed by the Croatian Science Foundation.

Luca Malatesti

In the last decade there has been a resurgence of interest in the insanity defence. One of the apparent moral truisms is that a person should not be blamed for actions they are not responsible for. As an instantiation of this principle, the moral rationale for the insanity defence is to prevent unjustly punishing offenders who are not responsible due to a mental illness.

Across the Western hemisphere, formulations of the insanity defence usually involve two components. One component, that we call the incapacity clause, states that a person is not accountable if, when committing the crime, she lacked some relevant psychological capacities, such as the cognitive ability to understand the nature of her action and the ability to control her behaviour in the light of that knowledge. For instance, if due to a delusion, someone kills a person thinking that he is helping her, he is unaccountable because he did not know the nature of his action. The other component of the insanity defence, that we call the mental illness clause, requires that these incapacities are caused by a mental illness.

Gerben Meynen

Despite the common-sense view that the insanity defence presupposes the mental illness clause, legal scholars and philosophers debate whether this is the case. Some argue that the mental illness clause is not important for determining criminal responsibility because mental illness is neither sufficient nor necessary for determining whether someone should be excused for a crime. A judgment on her mental incapacity should be enough. Moreover, in recent years the Convention on the Rights of Persons with Disability (CRPD) has sparked additional discussion. According to some interpretations of the convention, not only the mental illness clause, but the insanity defence as such should be abolished because it discriminates against disabled individuals.

Marko Jurjako

In the paper, we focus our discussion on the role that mental illness clause should play within legislations that adopt some form of the insanity defence. Thus, we do not directly discuss issues raised by the adoption of the CRPD. After providing a preliminary discussion of the rationale for having the insanity defence, we focus on the proper role of the mental illness clause in it.

We aim to offer a nuanced discussion whether the mental illness clause should be retained as a component of the insanity defence. In this regard, we discuss three principal reasons why the clause is important for adjudicating cases of criminal non-responsibility. 

The first reason relates to our exculpatory practices. In some cases, the presence of a mental illness indicates an internal impairment in decision-making capacities that undermines legal culpability in a way that cannot be attributed to any other cause outside the agent. In this sense, a mental illness can provide a particular cause that explains why the agent is not responsible for her crime.

The second reason pertains to our epistemological practices and practical limitations when trying to determine the accountability of a defendant. We argue that knowing whether a defendant is suffering from a specific mental illness can be especially helpful for establishing whether the agent at the time of the act had relevant incapacities. For instance, if the defendant suffers from schizophrenia, that gives us reason to examine whether she could have committed the crime while suffering from a paranoid delusion.

The third reason pertains to the general relation between legal practice and medical psychological and scientific advancements in the study of human behaviour. We maintain that the mental illness clause keeps a close tie between the relevant sciences of the mind and the law. Thus, it enables an interactive relationship that secures the conceptual and evidentiary relations between the clinical advancements and its scientific overlays with ethically justifiable legal practices. 

For instance, future studies might confirm that a certain subgroup of individuals with antisocial personality disorder suffer from such mental/brain incapacities that their criminal actions may be the result of dysfunctionalities in their neurophysiology. This scientific evidence would give us reason to conclude that despite the appearances of ill will, a subgroup of defendants with severe forms of antisocial personality might not be accountable for some of their crimes. 

The main outcome of our discussion is that an ethically justified formulation of the insanity defence need not necessarily include an explicitly stated mental illness clause. Nonetheless, we argue that the ethically justified formulations of the insanity defence should be able to accommodate the reasons underlying the adoption of this clause. 

Thus, our main conclusion is that different legislations might serve criminal justice solely based on the incapacity defence without a formal adoption of the mental illness clause. Depending on their other safeguards, these legislations should allow, however, that mental illness plays at least an evidentiary role in the incapacity defence.