Burden and Standard of Proof in Nigeria: Who Must Prove What, and How Much?

Walk into any criminal court in Nigeria on any working day and you will hear the phrase “beyond reasonable doubt” used at least once. Walk into a civil court and you will hear “balance of probabilities.” Both phrases answer a single question: how much proof does a party need before a court will rule in their favour? That question, and the related question of who has to do the proving, is what the law on burden and standard of proof is all about.

These concepts are not just examination topics. In the real world, getting them wrong costs people their cases and sometimes their freedom. A prosecutor who does not understand where the burden lies may present an incomplete case and watch a conviction collapse on appeal. A defence counsel who does not understand the shifting evidential burden may miss the moment when the accused needs to say something in response to the prosecution’s case.

This article works through the nature of the burden of proof, the difference between the legal burden and the evidential burden, how the burden operates in criminal and civil cases, the standard required to discharge it, and the situations where the burden shifts or is placed on the accused from the beginning.

What is Proof?

Proof in the law of evidence is the allegation of facts and circumstances that convince a court of the truth of those allegations. It is the method by which the existence or non-existence of a fact is established to the satisfaction of the court.¹

Proof is not the same as evidence. Evidence is the means by which facts are established. Proof is the result. When the prosecution adduces enough evidence to satisfy the court beyond reasonable doubt, it has achieved proof. The evidence was the tool. Proof is the outcome.

The Two Senses of Burden of Proof

The burden of proof is understood in two different senses in Nigerian evidence law. Confusing these two is one of the most common examiner complaints, and students who distinguish them clearly immediately stand out.

The Legal Burden (Persuasive Burden)

The legal burden is the obligation imposed by law on a party to persuade the court, either by the preponderance of evidence in civil cases or beyond reasonable doubt in criminal cases, that the material facts constituting the whole of their case are true.² It is governed by sections 131 and 132 of the Evidence Act 2011.

The legal burden is sometimes called the burden on the pleadings or the persuasive burden. Its defining characteristic is that it is fixed. It does not move. It rests on the same party throughout the entire trial from beginning to end.³ In a criminal case, the legal burden of proving guilt rests on the prosecution from the moment the accused is charged until the verdict is delivered. It never moves to the accused. In Duru v Nwosu,⁴ the court affirmed that the legal burden is stable and remains with the party on whom it is placed regardless of what happens at trial.

In Cyril Areh v C.O.P,⁵ the court stated it plainly: the burden of proof lies upon the party who substantially asserts the affirmative of the issue and in criminal cases, the presumption of innocence casts on the prosecution the burden of proving every ingredient of the offence.

The Evidential Burden (Secondary Burden)

The evidential burden is different. It is the obligation of a party to adduce sufficient evidence on a particular fact or issue to give the court a reasonable basis to decide the matter in their favour.⁶ Unlike the legal burden, the evidential burden shifts. It moves from party to party as the trial progresses, depending on the state of the evidence at any given moment.

When a party bearing the evidential burden adduces sufficient evidence on a point, the opponent then comes under an evidential burden to call evidence in reply or face an adverse finding on that point. This process of shifting the evidential burden back and forth continues throughout the trial.

Sections 136 and 140 of the Evidence Act 2011 govern the evidential burden. In Wok v University of Uyo,⁷ the court confirmed that the evidential burden can shift from one party to the other in the course of proceedings.

The critical distinction to carry into any examination answer is this: the legal burden never shifts once fixed; the evidential burden shifts throughout the trial.

The Basic Rule: He Who Asserts Must Prove

Section 131 of the Evidence Act 2011 states the foundational rule. Whoever desires any court to give judgment as to any legal right or liability dependent on the existence of facts which they assert must prove that those facts exist.

The corresponding rule in section 132 states that the burden of proof in a suit or proceeding lies on that person who would fail if no evidence at all were given on either side.

This test in section 132 is the most reliable way to identify who carries the legal burden at the outset of any case. Ask yourself: if neither party called any evidence at all, who would lose? That party bears the burden.

In a criminal case, if the prosecution called no evidence, the accused would be acquitted. The prosecution therefore bears the legal burden. In a civil case, if neither side called evidence, the plaintiff would fail because the plaintiff is asserting a claim that has not been proven. The plaintiff therefore generally bears the legal burden.

In Nigerian Army v Yakubu,⁸ the Supreme Court restated the principle: a party who asserts must prove. In Olufosoye v Fakorede,⁹ the court held that he who asserts an allegation, whether affirmative or negative, must prove it.

The rule applies whether the assertion is positive or negative. A party does not escape the burden of proof merely because they are making a negative allegation.

Burden of Proof in Criminal Cases

The General Rule: The Prosecution Proves Everything

In criminal proceedings, the general rule is that the burden of proving the guilt of the accused rests entirely on the prosecution. The prosecution must prove each and every ingredient of the offence charged.

This rule has a constitutional foundation that goes beyond the Evidence Act. Section 36(5) of the 1999 Constitution of Nigeria provides that every person charged with a criminal offence shall be presumed innocent until proved guilty according to law. This constitutional presumption of innocence means that an accused person starts every trial with the benefit of innocence, and the prosecution must work to displace that presumption through evidence. If the prosecution fails to do so, the accused must be acquitted, regardless of suspicion.

In Onafowokan v The State,¹⁰ the Supreme Court held that the primary onus of establishing the guilt of the accused is always on the prosecution except in very special and limited circumstances. The court confirmed that the burden of proving an alibi set up by an accused is not on the accused but on the prosecution to disprove.

In R v Oladipo Osunbiyi,¹¹ the Federal Supreme Court held that the accused does not bear the onus of proving the defences of self-defence, accident, or provocation. These are matters the prosecution must exclude through its evidence.

What this means in practice is that once an accused raises a defence such as alibi, self-defence, or accident, the prosecution must call evidence to negative that defence. It is not enough to simply assert that the defence is false. The prosecution must prove it beyond reasonable doubt.

The Standard in Criminal Cases: Beyond Reasonable Doubt

Section 135(1) of the Evidence Act 2011 sets out the standard. If the commission of a crime by a party to any proceeding is directly in issue in any proceeding, civil or criminal, it must be proved beyond reasonable doubt.

What does beyond reasonable doubt mean? The courts have consistently refused to define it precisely, on the grounds that any attempt at definition is more likely to confuse than to clarify. What is clear from the case law is what it does not mean. It does not mean absolute certainty. It does not mean proof beyond any conceivable doubt, however fanciful or remote.

In Osagiede v The State,¹² the court held that the burden of proof lies on the prosecution and it never shifts. On the whole of the evidence, if the court is left in doubt, the prosecution has failed to discharge its burden and the accused is entitled to acquittal.

The phrase “benefit of the doubt” captures the operation of the standard. Where the court, having heard all the evidence, is not sure whether the accused committed the offence, the accused benefits from that doubt and must be acquitted. A court must not convict on suspicion however deep. In R v Griliopoulous,¹³ the court held that suspicion, however deep, cannot ground a conviction.

Exceptions: When the Accused Bears a Burden

The general rule that the prosecution proves everything has several exceptions where the burden shifts to or is initially placed on the accused.

The most significant exception is insanity. The law presumes every person to be sane. An accused who raises the defence of insanity must prove that defence. Section 139(3)(c) of the Evidence Act 2011 places the burden of proving insanity on the accused. The rationale is that sanity is presumed, so the person who asserts the contrary must prove it. See sections 28 and 29 of the Criminal Code for the circumstances in which the defence of insanity can be raised.

Similarly, the defence of intoxication is a matter that the accused must prove when raised. Section 139(3)(c) of the Evidence Act 2011 covers this alongside insanity.

Special pleas under section 36(9) of the Constitution are also the accused’s burden. If an accused claims autrefois acquit (that they have already been acquitted of the same offence) or autrefois convict (that they have already been convicted of the same offence), the burden of proving those facts lies on the accused.

Where other statutes create reverse burdens, those must also be observed. Section 417(c) of the Criminal Code places on the accused the burden of proving a lawful excuse for possessing housebreaking instruments at night. Section 60 of the Pharmacy Act 1958 places on a person found in possession of a poisonous substance the burden of proving lawful possession. In Queen v Ohaka,¹⁴ the court upheld the conviction where the accused failed to discharge that burden. Section 166(2)(b) of the Customs and Excise Management Act 1958 similarly places on a person found with contraband the burden of proving lawful importation, as confirmed in Fugu v Board of Customs and Excise.¹⁵

In Christopher Oti v IGP,¹⁶ the court held that the burden of proving that an accused had a licence for a firearm rested on the accused, as it was a fact personally within his knowledge. This is the “special knowledge” exception: where a fact is peculiarly within the knowledge of one party, that party may bear the burden of proving it.

The constitutional tension in all of this is real and not always frankly discussed. Section 36(5) of the 1999 Constitution says every accused is presumed innocent. Statutory reverse burdens effectively require the accused to prove their innocence on particular matters. Nigerian courts have generally upheld these reverse burdens on the basis that they are consistent with the constitutional provision, which itself acknowledges that burdens can be placed on the accused by law. But the tension between the presumption of innocence and statutory reverse burdens remains an unresolved doctrinal question in Nigerian jurisprudence that well-read students should acknowledge.

Burden of Proof in Civil Cases

In civil proceedings, the general rule is that the burden of proof rests on the plaintiff. The plaintiff must prove all the positive allegations in their statement of claim that the defendant has denied.

Section 132 of the Evidence Act 2011 provides that the burden of proof in a suit lies on that person who would fail if no evidence at all were given on either side. As stated in Olufosoye v Fakorede,⁹ the plaintiff who asserts a claim bears the burden of proving the facts on which the claim is based.

The defendant must prove any particular defence they raise. If the defendant pleads contributory negligence in a negligence action, the burden of proving contributory negligence rests on the defendant. In Sunday Uzokwe v Dansy Industries Nig Ltd,¹⁷ the court confirmed that the incidence of the legal burden in civil cases depends substantially on the nature of the defence raised.

Pleadings are crucial in determining the burden in civil cases. It is the pleadings that reveal what facts are in issue and which party is asserting them. A fact alleged in the statement of claim but admitted in the statement of defence is no longer in issue. A fact denied becomes a fact in issue, and the party asserting it bears the burden of proving it.

The Standard in Civil Cases: Balance of Probabilities

In civil proceedings, the standard of proof is proof on the balance of probabilities, also called the preponderance of evidence.

This standard requires that the evidence supporting a party’s case must be more probable than not. If the court thinks it is more likely than not that the fact asserted is true, the party has discharged the civil burden. Unlike the criminal standard, this does not require the court to be sure. It merely requires the court to be more persuaded by one side than the other.

The Special Rule for Criminal Acts in Civil Proceedings

An important nuance in section 135 of the Evidence Act 2011 is that where the commission of a crime is directly in issue in a civil proceeding, it must be proved beyond reasonable doubt even in that civil proceeding. This arises in situations such as fraud claims, defamation actions where the defendant justifies by truth and truth requires proof of a criminal act, or civil claims where one party alleges the other committed forgery or perjury. In those situations, the criminal standard applies even though the proceeding is civil.

The Shifting of the Burden

Section 139 of the Evidence Act 2011 provides that the burden of proof as to any particular fact may in the course of a case shift from one side to the other.

To understand shifting clearly, use this example. In a civil land dispute, the plaintiff asserts ownership. Initially, the plaintiff carries both the legal and evidential burden. The plaintiff opens their case and leads evidence of title. At this point, the plaintiff has discharged their initial evidential burden. The evidential burden then shifts to the defendant to call evidence in reply. If the defendant does nothing, the court is entitled to give judgment for the plaintiff.

But the legal burden of proving ownership rests with the plaintiff throughout. If at the end of the case the evidence is perfectly balanced, the plaintiff loses. The legal burden never moves.

In Okunola v Oduola,¹⁸ the court held that the plaintiff had not discharged the initial burden of proof so as to shift the evidential burden to the defendant. This is an example of the evidential burden never getting to shift because the party who carried it first failed to discharge it at all.

In Onyema v Amah and Nigerian Maritime Service Ltd v Bello Afolabi,¹⁹ the courts affirmed that the burden of proof on a particular fact shifts in the course of a case as parties adduce evidence.

The operation of res ipsa loquitur in negligence cases gives rise to an apparent shift of the evidential burden. Where the facts of a case raise an inference of negligence without the need for specific evidence, the defendant comes under a practical obligation to call evidence disproving negligence or face judgment going against them. This is the evidential burden shifting as a result of an inference raised by proved facts.

A Quick Reference Table

Concept	Meaning	Key Section	Notes
Legal Burden	Obligation to persuade the court; does not shift	ss 131 to 132 EA 2011	Also called persuasive burden or burden on the pleadings
Evidential Burden	Obligation to adduce sufficient evidence on a point; shifts	ss 136, 139 to 140 EA 2011	Shifts back and forth throughout trial
Beyond Reasonable Doubt	Standard in criminal cases; prosecution must make court sure of guilt	s 135(1) EA 2011; s 36(5) CFRN	If court is in doubt, accused is acquitted
Balance of Probabilities	Standard in civil cases; more probable than not	s 134 EA 2011	Lower standard than criminal
Criminal Acts in Civil Cases	Criminal standard applies even in civil proceedings	s 135(1) EA 2011	Eg: fraud claims, defamation justifications
Reverse Burden	Where accused bears burden on specific matters	s 139(3) EA 2011; statutes	Insanity, intoxication, special knowledge
Constitutional Presumption	Every accused presumed innocent until proved guilty	s 36(5) CFRN 1999	Foundation of criminal burden rule

Key Cases

Cyril Areh v C.O.P The court held that the burden of proof lies on the party who substantially asserts the affirmative and in criminal cases the presumption of innocence casts on the prosecution the burden of proving every ingredient of the offence.

Onafowokan v The State (1987) 3 NWLR (Pt. 61) 538 The Supreme Court held that the primary burden of establishing guilt is always on the prosecution. The burden of disproving an accused’s alibi is not on the accused.

R v Oladipo Osunbiyi (1961) 1 All NLR 56 The Federal Supreme Court held that an accused does not bear the burden of proving defences of self-defence, accident or provocation.

Duru v Nwosu (1989) 4 NWLR (Pt. 113) 24 The court confirmed that the legal burden is stable and does not change throughout the trial. It rests throughout on the party on whom it is initially placed.

Osagiede v The State (1995) 1 NWLR (Pt. 373) 532 The court held that the burden of proof lies on the prosecution and never shifts in criminal cases. If the court is left in doubt, the prosecution has failed and the accused must be acquitted.

Olufosoye v Fakorede (1993) 1 NWLR (Pt. 272) 747 The court held that he who asserts must prove. The burden of proof lies on the plaintiff who is asserting the claim.

Okunola v Oduola (1981) NSCC 206 The court held that the appellant had not discharged the initial burden of proof sufficiently to shift the evidential burden to the respondent.

Problem Question Framework

When a problem question raises issues of burden of proof, apply this structure.

First, identify the type of proceeding. Is it criminal or civil? In criminal proceedings, start with section 36(5) of the Constitution and the prosecution’s burden of proving every element of the offence. In civil proceedings, start with section 132 and the plaintiff’s burden.

Second, identify the legal burden holder. Apply the section 132 test: who would lose if no evidence at all were given on either side? That party bears the legal burden.

Third, check whether any exception or reverse burden applies. If the accused raises insanity, intoxication, or a special plea, or if a specific statute places a burden on the accused, identify the relevant provision and state its effect.

Fourth, address the shifting of the evidential burden. As the problem question scenario unfolds, note each point where one party has adduced sufficient evidence to shift the evidential burden to the other side.

Fifth, apply the correct standard. Beyond reasonable doubt for criminal proceedings and for proof of criminal acts in civil proceedings. Balance of probabilities for other civil proceedings.

Sixth, apply the constitutional dimension. If the prosecution’s evidence appears to have been obtained through coercion or if the accused was denied the opportunity to answer allegations, engage section 36 of the 1999 Constitution alongside the statutory analysis.

Common Student Mistakes

The most common mistake is treating the legal burden and the evidential burden as the same thing. They are not. The legal burden is fixed. The evidential burden moves. Students who write “the burden shifts to the accused when the prosecution has made a prima facie case” without distinguishing the two types of burden are producing an imprecise answer.

The second mistake is stating that the standard of proof in criminal cases is “beyond all doubt.” It is beyond reasonable doubt, not beyond all conceivable doubt. Certainty is not required. The court must simply be sure, meaning free from reasonable doubt, not free from every possible doubt.

The third mistake is forgetting the constitutional dimension of the criminal burden. Section 36(5) of the 1999 Constitution is not just background. It is a directly applicable provision that generates an enforceable right. An accused who is convicted without the prosecution proving every element of the offence has had their constitutional right violated, not just an evidential rule breached.

The fourth mistake is treating the reverse burden exceptions as creating a full transfer of the legal burden to the accused. In most cases, the accused who bears a reverse burden only needs to discharge it on the balance of probabilities, not beyond reasonable doubt. The legal burden of proving guilt overall remains on the prosecution.

The fifth mistake is forgetting that the ultimate burden in criminal cases never shifts. In Osagiede v The State, the court was emphatic. Even when an accused raises defences that place an evidential burden on them, the prosecution’s overall burden of proving guilt beyond reasonable doubt never moves.

---

Footnotes

¹ Evidence Exam Answers, Law of Evidence I (University of Ibadan Faculty of Law, 2021) 12.

² Evidence Act 2011, ss 131 to 132; S A Fagbemi, Law of Evidence I: Lecture Notes (University of Ibadan 2021) 32.

³ Duru v Nwosu (1989) 4 NWLR (Pt. 113) 24.

⁴ ibid.

⁵ Cyril Areh v C.O.P (1966) NMLR 67.

⁶ Evidence Act 2011, ss 136, 139 to 140; Wok v University of Uyo (2009) 8 NWLR (Pt. 1142) 1.

⁷ Wok v University of Uyo (2009) 8 NWLR (Pt. 1142) 1.

⁸ Nigerian Army v Yakubu (2013) 5 SCM 209.

⁹ Olufosoye v Fakorede (1993) 1 NWLR (Pt. 272) 747.

¹⁰ Onafowokan v The State (1987) 3 NWLR (Pt. 61) 538.

¹¹ R v Oladipo Osunbiyi (1961) 1 All NLR 56.

¹² Osagiede v The State (1995) 1 NWLR (Pt. 373) 532.

¹³ R v Griliopoulous (1959) WRNLR 93.

¹⁴ Queen v Ohaka (1962) NRNLR 65.

¹⁵ Fugu v Board of Customs and Excise (1966) NMLR 129.

¹⁶ Christopher Oti v IGP (1958) NRNLR 1.

¹⁷ Sunday Uzokwe v Dansy Industries Nig Ltd (1985) 1 NWLR (Pt. 4) 668.

¹⁸ Okunola v Oduola (1981) NSCC 206.

¹⁹ Onyema v Amah (1993) 6 NWLR (Pt. 303) 731; Nigerian Maritime Service Ltd v Bello Afolabi (1978) 2 SC 79.