Defence of Insanity: Burden on the Accused Person to Establish


In the Supreme Court of Nigeria Holden at Abuja On Friday, the 5th day of June, 2020 Before Their Lordships

Mary Ukaego Peter-Odili

Musa Dattijo Muhammad

Kudirat Motonmori Olatokunbo Kekere-Ekun

Chima Centus Nweze

Ejembi Eko

Justices, Supreme Court



Samuel Addo … … … … … Appellant


The State … … … … … … Respondent

(Lead Judgement delivered by Honourable Mary Ukaego Peter-Odili, JSC)


The Appellant attended a monthly church meeting which holds on the first day of every month at a hilltop called Ori Oke Rele, Ife Road, Ondo State. On the 2nd Day of November, 2009, the Appellant discovered his belongings had been tampered with at the hilltop and he challenged the Pastor-in-charge, whom he already believed had “changed his glory”. The Pastor whipped and threw a church bell at him. He got angry, and used the bell to beat the Pastor to death. Upon realising an old woman present at the scene had witnessed what he did, he used a stone to hit the woman until she died. The Appellant was later arrested by the Police within the vicinity of the hilltop and he made three confessional statements at the Police station dated 4th, 6th and 8th November, 2009. In the statements, the Appellant gave graphic details of the incident.

Subsequently, the Respondent preferred a Charge of murder contrary to Section 316 and punishable under Section 319 of the Criminal Code, Cap 30, Vol. II, Laws of Ondo State, against the Appellant. Both parties called witnesses, and the Appellant raised the defence of insanity and alibi. At the conclusion of trial, the Appellant was convicted and sentenced to death by hanging. He unsuccessfully appealed to the Court of Appeal, and this led to a further appeal to the Supreme Court.

Issue for Determination

The following issue, as extrapolated from the issues formulated by the parties, was the sole issue determined by the Supreme Court:

Whether the Prosecution proved its case against the Appellant beyond reasonable doubt.


Counsel for the Appellant prefaced his argument with the submission that the Prosecution did not prove the guilt of the Appellant beyond reasonable doubt, in that the Appellant was not arrested at the scene of the crime, and there was nothing linking him to the death of the deceased to the exclusion of all other persons or possibilities. Counsel contended that there were inconsistencies in the evidence given by the Prosecution witnesses as to the recovery of the alleged weapon (the bell), which raised reasonable doubt in the Prosecution’s case which should be resolved in favour of the Appellant. He cited the case of EGWUMI v STATE (2013) All FWLR (Pt. 678) 824 at 846. Counsel argued further that the act of the accused was not intentional with the knowledge that death or grievous bodily harm was a probable consequence, as the defence of mental disorder raised at the Appellant’s arrest was a sufficient defence to show that he acted at a moment of insanity. He cited JIMMY v STATE (2014) All FWLR (Pt. 714) 104 at 117 in support of his submission. He added that the Prosecution could not rely on circumstantial evidence to sustain the conviction, as the factors for such application do not exist in this case; rather, what exists is suspicion which cannot ground a conviction. Counsel concluded that the Prosecution did not rebut the defence of insanity raised by the Appellant, and the lower courts erred in convicting the Appellant based on the confessional statements in light of the defence of insanity.

In response, counsel for the Respondents contended that the onus of proving insanity was on the accused person who pleads it as a defence, and the Appellant in this case failed to prove same on balance of probability. He contended further that the Prosecution disproved the defence of insanity, and the defence of alibi was raised too late to be taken seriously. Counsel submitted in addition, that the confessional statements showed clearly that the Appellant murdered the deceased persons, and this is supported by the post mortem results. He cited ISANG v STATE (1996) 2 NWLR (Pt. 473) 458 at 468. It was also his argument, that the inconsistencies in the evidence of the Prosecution were not material, and the evidence of the Prosecution witnesses provided corroboration. He maintained that the evidence of the Prosecution witnesses together with the extra-judicial statements of the Appellant, established his guilt beyond reasonable doubt, and the trial court correctly relied on circumstantial evidence in view of the absence of a direct eyewitness. Finally, counsel contended that an accused person, such as the Appellant, cannot deny involvement in a murder, and at the same time raise the plea of insanity. He cited the case of PETER v STATE (2007) 5 ACLR 207, in support of this submission.

Court’s Judgement and Rationale

In respect of the Appellant’s defence of alibi, the Supreme Court held that the defence of alibi exculpates a Defendant from a crime committed since he was not the one who committed it as he was elsewhere. However, alibi has no utilitarian value if raised at the trial for the Police would be hampered in such a way that they cannot inquire into where the accused was outside the crime location. The court found that the Appellant was arrested within the vicinity of Ori-Oke Rele, and he made three statements in which he did not mention an alibi. The defence of alibi was not raised at the earliest opportunity that would give the Police the chance to investigate it, and this left the lower courts with no option but to ignore it – SMART v STATE (2016) 9 NWLR (Pt. 1518) 447.

On the inconsistency in the evidence of the Prosecution witnesses in respect of the murder weapon, the Supreme Court found that there was no contradiction in the evidence of the Prosecution witness; rather, the evidence of the witnesses corroborated each other, and the evaluation made by the trial court is not dented.

Deciding the issue of proof of murder by the Prosecution, their Lordships held that the ways of proving the ingredients of murder are by: (a) evidence of eye witness; (b) confessional statement of the accused person stating unequivocally that he committed the offence charged; and (c) circumstantial evidence – BILLIE v STATE (2016) 15 NWLR (Pt. 1536) 363. From the record, there was no eye witness; therefore, the court had to look at the confessional statements of the Appellant and circumstantial evidence before it. It is the law that where direct evidence of an eye witness is not available, the court may infer from the facts proved, the existence of other facts that may logically tend to prove the guilt of the accused person. In this case, the Appellant failed to discredit the pieces of evidence which made up the unbroken chain of evidence which left the lower courts with no option but to see the circumstantial evidence in the light akin to direct evidence, and to conclude that the ingredients of the offence of murder of the two victims were proved beyond reasonable doubt. The court cited PETER v STATE (1997) LPELR -2912.

In respect of the Appellant’s defence of insanity, the court held that the onus of proving insanity is on the Appellant, and burden is discharged on balance of probability by showing that the Appellant was suffering from mental disease or from natural mental infirmity at the relevant time which deprived him of capacity to – (a) understand what he was doing; (b) control his actions; and (c) know that he ought not to do the act or make the omission. Once any of these ingredients is proved, then there was no consent of will and his act is not punishable as a crime. However, where the evidence of the accused’s mental stability is suspect, he will not be taken seriously and the evidence will be rendered idle. The court relied on Section 27 of the Criminal Code to the effect that every person is presumed to be of sound mind at any relevant time until the contrary is proved. In this case, the Appellant’s defence of insanity is curious, as the Appellant’s statements were made with clarity, detailed and certainly rendered by a person of sound mind. The facts stated therein tallied with the medical reports on the injuries on the deceased, and same corroborated the evidence of the Prosecution witnesses.

Appeal Dismissed.


Dr. Oladoyin Awoyale with Adetayo Adeyemi, Esq. and A.B. Daramola, Esq. for the Appellant.

F. Omotosho Esq. for the Respondent with the fiat of the Attorney-General of Ondo State.

Reported by Optimum Publishers Limited, Publishers of the Nigerian Monthly Law Reports (NMLR)(An Affiliate of Babalakin & Co.)


“…… the onus of proving insanity is on the Appellant, and burden is discharged on balance of probability by showing that the Appellant was suffering from mental disease or from natural mental infirmity at the relevant time……”