1. Burden and standard of proof

In a criminal case the prosecution must prove every ingredient of the offence. The accused does not have to prove that he is innocent. There are three reasons. Section 23(4) of the Constitution of Sierra Leone 1991 gives him the presumption of innocence. The person who asserts a fact is the person who must prove it. And there is no equality of arms: the State has the investigators, the lawyers and the resources.

The leading case is Woolmington v DPP. Reginald Woolmington admitted that he shot his wife. His defence was accident. The trial judge told the jury that, once the prosecution had shown that she died from the shot, it was for him to satisfy them that it was an accident. The Court of Criminal Appeal agreed. The House of Lords did not. Viscount Sankey said that the prosecution must prove the prisoner's guilt, subject to the defence of insanity and to any statutory exception. Kargbo v R, in the Court of Appeal, is the Sierra Leone authority for the same rule. Musa Sesay and Four Others v The State is the Gambian authority.

The burden does not shift. Where the accused has to prove insanity, or a statutory exception, he proves only that issue. Every other ingredient stays with the prosecution, and stays at the criminal standard.

Insanity is a common-law exception, not a creature of a modern statute. It is proved within the M'Naghten Rules of 1843. R v Sodeman is authority that the accused proves it on the balance of probabilities. If he succeeds, the verdict is not guilty by reason of insanity.

Unfitness to plead sits beside insanity. It is usually the defence that raises it, and the defence then proves it on the balance of probabilities. Podola is sometimes remembered as a German accused of murder who said he could not follow an English trial. The report is narrower. Podola was charged with the murder of a detective sergeant and claimed a hysterical loss of memory. The Court of Criminal Appeal held that the burden is on the defence, on the balance of probabilities, and that loss of memory of the crime is not unfitness if the accused can still understand the trial and instruct his lawyers. If the prosecution raises unfitness, R v Robertson says the prosecution must prove it beyond reasonable doubt. The judge may raise the issue as well.

Some English statutes put a legal burden on the accused in express words. The list is section 1 of the Prevention of Crime Act 1953 (an offensive weapon in a public place, and the accused must show lawful authority or reasonable excuse); section 2(2) of the Homicide Act 1957 (diminished responsibility, and R v Dunbar); section 30(2) of the Sexual Offences Act 1956 (living on immoral earnings); section 2 of the Prevention of Corruption Act 1916 (a gift to a public officer, and the accused must show it was not corrupt); section 30(2) of the Bills of Exchange Act 1882; section 5 of the Dangerous Dogs Act 1991; section 5(2) of the Road Traffic Act 1988; and section 28(2) of the Larceny Act 1916. These are English examples. They are not Sierra Leone Acts.

Other statutes do it by implication. Section 101 of the Magistrates' Courts Act 1980 is the example, and the 1952 Act is to the same effect. Where the accused relies on an exception, exemption, proviso, excuse or qualification, he must prove it. The drafting clues are words such as "except", "exempt", "excuse" and "provided that". Ease of proof matters too. It is easier for a driver to produce a licence than for the prosecution to prove that none exists. Gatland v Metropolitan Police Commissioner, Machin v Ash and John v Humphreys are the illustrations, and the standard is the balance of probabilities, as in R v Carr-Briant.

R v Edwards is the worked example. Edwards was convicted of selling intoxicating liquor without a licence, contrary to section 160 of the Licensing Act 1964. He said the prosecution had called no evidence that he had no licence. The Court of Appeal held that the statute put that fact on him. The prosecution still had to prove the rest.

R v Hunt shows the limit. Hunt was charged under section 5 of the Misuse of Drugs Act 1971. The Misuse of Drugs Regulations 1973 took out of that section a preparation of morphine containing not more than 0.2 per cent. The prosecution proved powder in his possession and did not prove the percentage. He pleaded guilty after a ruling against him. The House of Lords allowed the appeal. Edwards was correctly decided, but a court is slow to read a statute as making an accused prove his innocence, especially on a serious drugs charge. If the wording is genuinely ambiguous, the doubt is resolved for the accused. Here the prosecution had to prove that the powder was over the permitted strength.

Nimmo v Alexander Cowan & Sons Ltd is the civil guide to the same drafting question. A workman was injured and relied on section 29(1) of the Factories Act 1961, which required the place of work to be made safe "so far as is reasonably practicable". The House of Lords divided three to two. The majority held that the employer, not the workman, had to prove that it was not reasonably practicable to make the place safer. The case turns on the words of the statute and on the split in the House. The holding is the employer's burden, not a burden on the injured man.

Common-law defences other than insanity are different. They raise an evidential burden only. The accused must lay a foundation, enough to put the defence before the jury. If he does not, the jury never considers it. If he does, the prosecution must disprove it beyond reasonable doubt. The list is provocation (Mancini v DPP, 1942), self-defence (R v Lobell, 1957), duress (R v Gill), drunkenness (Kennedy v HM Advocate, 1944), non-insane automatism (Bratty v Attorney-General for Northern Ireland, 1963) and alibi (R v Johnson, 1961).

When the accused bears only an evidential burden, he does not have to prove the defence on the balance of probabilities. He lays a foundation. The prosecution must then disprove the defence beyond reasonable doubt. The balance of probabilities is the standard for a legal burden: insanity, unfitness when the defence raises it, and the statutory exceptions. Provocation and alibi are not legal burdens.

The standard of proof is the degree of persuasion the law requires of the side that bears the legal burden. For the prosecution, that degree is beyond reasonable doubt. Where the accused bears a legal burden, R v Carr-Briant holds that the standard is the balance of probabilities.

Miller v Minister of Pensions compares the two standards. Denning J, as he then was, said the criminal standard need not reach certainty, and need not exclude a shadow of a doubt. If the evidence against a man is so strong that the only possibility left in his favour is a remote one, which can be dismissed with the words "of course it is possible, but not in the least probable", the case is proved, but nothing short of that will do. The civil standard is proof that the fact is more probable than not. If the probabilities are equal, the party who bears the burden has failed.

How a judge should explain the criminal standard to a jury is a separate, practical question. R v Summers holds that the jury should be satisfied so that they are sure. R v Walters looks at the summing-up as a whole. R v Ferguson is a model direction. The phrase "beyond reasonable doubt" is the standard. A direction that leaves the jury unsure what it means is a ground of appeal.