The defence of insanity is recognised under Nigerian criminal law and can, where properly established, relieve an accused person of criminal responsibility for an offence.
The broader principles governing the defence have previously been discussed in our article, Insanity as a Defence in Nigerian Criminal Law, including the presumption of sanity, the burden and standard of proof, the evidence that may establish insanity, and the distinction between temporary and self-induced insanity.
The issue considered in this article is narrower:
What is the legal consequence when the defence of insanity is successfully established?
In ABDULLAHI v. STATE (2026) LPELR-83007(CA), the Court of Appeal considered the appropriate order to be made after finding that the appellant, by reason of insanity, was not guilty of the offence of culpable homicide punishable with death.
What Happened in ABDULLAHI v. STATE?
The Court accepted the defence of insanity and consequently found the appellant not guilty of the offence.
However, the Court rejected the argument that such a finding meant that the appellant should simply be released from custody.
The Court stated:
“…I find and hold that the appellant, by reason of insanity, is not guilty of the offence of culpable homicide punishable with death. But a finding of not guilty in such circumstances, contrary to the argument of counsel to appellant, does not result in an order releasing the said insane person from custody. The proper order is that such a person be placed in the custody and at such place at the pleasure of the Governor of the State. See Loke v. The State (1985) LPELR-1789(SC).”
ABDULLAHI v. STATE (2026) LPELR-83007(CA), per BOLOUKUROMO MOSES UGO, JCA, p. 16, paras. A–C.
The decision therefore establishes a clear point: a successful defence of insanity does not, by itself, mean that the accused person is immediately released from custody.
Not Guilty by Reason of Insanity Is Different from an Ordinary Acquittal
The distinction is important.
Ordinarily, where a criminal charge is not proved against an accused person, the result may be an acquittal and discharge.
But where the accused person is found not guilty by reason of insanity, the finding is based on a particular legal conclusion about the person’s mental state and criminal responsibility.
The court may find that the accused person is not criminally responsible for the act because of insanity, while the law nevertheless requires that the person remain in custody.
Therefore, the question of criminal responsibility must be distinguished from the question of what should happen to the person after the finding of insanity.
The decision in ABDULLAHI v. STATE demonstrates that these questions do not necessarily produce the same result.
What Happens After a Successful Defence of Insanity?
A successful insanity defence can prevent the accused person from being held criminally responsible for the offence. However, it does not follow that the person must immediately return to unrestricted liberty.
In ABDULLAHI, the Court of Appeal specifically held that the appropriate order was for the appellant to be placed in custody at such place at the pleasure of the Governor of the State.
The successful defence therefore does not operate as a simple escape from every form of legal restraint. The accused person avoids criminal liability for the offence on account of the established insanity, but the law can still provide for custody following that finding.
The precise procedure and form of custody, however, must be considered in light of the legislation applicable to the particular proceedings.
Insanity as a Defence Is Not the Same as Unfitness to Stand Trial
It is also important not to confuse a successful defence of insanity with the separate question of whether an accused person is fit to stand trial.
These are two different issues.
The defence of insanity concerns the accused person’s mental state at the time of the commission of the offence.
The question of fitness to stand trial concerns the accused person’s mental capacity to participate in the criminal proceedings and make a defence.
The Court of Appeal explained this distinction in AZUKA v. STATE (2021) LPELR-56553(CA).
The Court observed that a person who relies on insanity at the time of the commission of an offence does not automatically become incapable of standing trial. The question of fitness to stand trial may arise where the person’s unsoundness of mind continues to affect the person’s ability to understand the proceedings or defend himself.
The Court stated:
“I however consider it expedient to first observe that the Appellant would appear to be confusing the defence of insanity as raised by him in a criminal trial with the duty on the lower Court to determine his fitness to stand trial in respect of a criminal offence to wit: murder and in which he (Appellant) has raised the defence of insanity. In this regard, I consider it appropriate to further state that the fitness of a sane person accused of the commission of a criminal offence and who is not relying on the defence of insanity, to stand trial can become an issue which a trial Court has to determine where the insanity occurs post or after the criminal offence he is charged with. In other words, the insanity that has befallen such an accused person could have arisen after the commission of the offence charged. Where this is the case, a Court is expected to make a specific finding on the matter before it can properly proceed with trial. On the other hand, a person who relies on the defence of insanity as at the time of the commission of an offence, can only expect a Court to look into his fitness to stand trial, where the insanity or unsoundness is such that continues to affect his mental capacity to stand trial or defend himself. This is because there is no presumption of law that states that once a person is insane, he would always be deemed to be insane. Hence, it is not the position of the law that a person who sets up a defence of insanity at the time of the commission of the offence for which he is charged cannot be tried without the trial Court first determining his fitness to stand trial, if there is no evidence before the Court that the insanity which he relies upon is also militating against his standing trial for the said offence. In other words, that an accused person who relies on the defence of insanity could at his trial be very fit to stand trial once he does not exhibit any behaviour that puts the trial Court on notice or makes the trial Court to suspect that he might not be fit to stand trial because of his insanity or unsoundness of mind.”
AZUKA v. STATE (2021) LPELR-56553(CA), per AYOBODE OLUJIMI LOKULO-SODIPE, JCA, pp. 37–51, paras. F–C.
The distinction is therefore important: being insane at the time of committing an offence and being incapable of standing trial are not necessarily the same thing.
Why the Distinction Matters
An accused person could have been suffering from insanity at the time an offence was committed but subsequently be sufficiently mentally capable to participate in the criminal proceedings.
Conversely, a person who was sane when an offence was committed could subsequently become mentally incapacitated and unable to make a defence.
The legal questions in those situations are different.
The decision in AZUKA v. STATE emphasises that a court does not automatically have to treat an accused person as permanently incapable of standing trial merely because insanity has been raised as a defence.
There must be a basis for the court to suspect that the accused person’s mental condition affects his capacity to stand trial.
Conclusion
The defence of insanity can provide a complete defence to criminal responsibility where it is successfully established. But the legal consequences do not necessarily end with an ordinary acquittal and immediate release.
In ABDULLAHI v. STATE (2026) LPELR-83007(CA), the Court of Appeal found that the appellant, by reason of insanity, was not guilty of culpable homicide punishable with death. However, the Court made it clear that this finding did not result in an order releasing the appellant from custody.
Instead, the Court held that the proper order was for the appellant to be placed in custody at such place at the pleasure of the Governor of the State, relying on LOKE v. THE STATE (1985) LPELR-1789(SC).
The decision therefore highlights an important principle in Nigerian criminal law: a finding of not guilty by reason of insanity does not necessarily mean that the accused person walks free.
The question of criminal responsibility is distinct from the question of what protective or custodial measures may lawfully follow after insanity has been established.
Disclaimer
This article is for general informational purposes only and does not constitute legal advice. The applicable law and procedure may differ depending on the State, the offence charged and the legislation governing the proceedings. Readers seeking legal guidance on specific circumstances should consult a qualified legal practitioner.
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