2. Defendant’s evidential, legal burden, reverse burden of proof

2. Defendant’s evidential, legal burden, reverse burden of proof

As a general principle, a defendant does not have to prove his innocence. However, this principle is subject to certain exceptions, such as when the defendant seeks to rely on a defence or exception to liability, or when he needs to rebut a statutory presumption (situations where certain facts may be presumed true if the prosecution can prove other related matters).

A defendant’s defence may come from the prosecution witnesses (e.g., through cross-examination and questioning of the witnesses) or from the defendant himself or other sources.

Defendant’s evidential burden

A defendant will bear an evidential burden when he wants to rely on a general defence (apart from diminished responsibility and insanity, which are subject to a higher legal burden (see below)). The defence of duress, self-defence, provocation, and intoxication, must first be raised by the defence, but it is always for the prosecution to prove their case beyond a reasonable doubt, which involves negating the defence which has been set up.

As a general principle, the standard of evidential burden is one of which “might leave the jury a reasonable doubt”. If the fact-finding tribunal finds what the defence might have been true, then the defendant is entitled to be acquitted. Even if the fact-finding tribunal does not positively believe the defendant (or even if, on balance, the fact-finding tribunal prefers the prosecution witness’ version), the defence’s evidence may still raise a reasonable doubt about guilt. 

After this evidential burden is discharged by the defendant, the prosecution’s legal burden will start. Apart from demonstrating the core elements of the offences, it must go on to further disprove the defence.

Defendant’s Legal Burden

Once a legal burden is placed on a defendant, he would be required to prove on the balance of probabilities, i.e. it is more likely than not his version is true. The following are exceptional scenarios in which a legal burden is imposed on the defendant. 

1. Insanity

In cases where a defendant asserts insanity as a defence, the legal burden rests with the defendant. Exceptionally, if there is evidence meeting the criteria, a judge can on his own volition raises the issue to the jury. Conversely, if the prosecution raises issues about the defendant’s sanity, the burden of proof is on the prosecution to convince the jury to the criminal standard of beyond a reasonable doubt.

2. Diminished Responsibility

Section 3 of the Homicide Ordinance (Cap.339) provides a partial defence of diminished responsibility for the offence of murder. To put it simply, the defence has to prove, on the balance of probabilities, that (i) at the time of the killing, the defendant was suffering from an abnormality of mind, and (ii) the abnormality of mind substantially impaired the defendant’s mental responsibility in the killing. The burden on the defence is discharged if the evidence is justified on the balance of the probabilities in favour of the defence. It is for the prosecution to rebut the existence of such a defence beyond a reasonable doubt.

3. Express Statutory Provisions

The general principle is that if there is a statutory defence, and the defendant chooses to rely on such defence, the defendant would have to be responsible for proving that defence. Whenever the prosecution seeks to rely on this exception to legal burden, the court must construe the enactment under which the charge is laid, pursuant to section 94A of the Criminal Procedure Ordinance (Cap. 221).

Reverse Burden of Proof

A reverse burden of proof (reverse onus) means that a defendant is imposed with a burden to prove any matter or fact related to the offence. The starting point is that there is some objective policy justification for it. For instance, section 47(1)(a) of the Dangerous Drugs Ordinance (Cap. 134) stipulates that any person who is proven to have had in his physical possession anything containing or supporting a dangerous drug shall, until the contrary is proved, be presumed to have had such drug in his possession. The general presumption that the prosecution has to prove both actus reus (the guilty act or omission) and mens rea (the prohibited state of mind) is therefore displaced since the latter is presumed upon the proof of the former. The basis for this justification is that sophisticated drug smugglers, dealers, and couriers typically conceal drugs in some container, allowing the person in possession of the container to claim ignorance of its contents. Such defences are common and present real challenges for the police and prosecuting authorities.

From the ruling in Hin Lin Lee v HKSAR and Kulemesin v HKSAR, the court will take into account four important factors before imposing a reverse onus:

1. Statutory language: unless the statutory wordings state clearly or by necessary implication regarding the effect of the statute that it intends to reverse the onus to the defendant, the prosecution has to bear the burden of proof.

    

2. Nature of the offence created by the statutory provisions: the more serious the offence in terms of penalty and social obloquy, the less likely it is that the presumption of mens rea will be held to have been displaced, meaning that the prosecution must prove knowledge, intention or recklessness as to every element of the offence.

    

3. Policy considerations: the court must first consider whether the statutory purpose of a provision can be satisfactorily met if it requires the prosecution to prove mens rea.

An example of a rule that seeks to encourage social condemnation of a particular act is the strict liability imposed when a man has sexual intercourse with an underage girl, regardless of the defendant’s knowledge of the girl’s legal age or whether the girl consented. The deterrent effect of the criminal law is not limited to deterring people from engaging in known unlawful activities; it also encourages individuals to take precautions to avoid potentially unlawful actions. In this context, taking care to avoid potential unlawful actions would significantly enhance the protection provided for young girls by the section.

Moreover, the courts are hesitant to allow corporate entities to evade liability when public safety concerns are paramount. For instance, in the interest of public safety in maintaining a gondola properly, the lack of mens rea in committing a criminal offence by an individual is not a relevant concern. Otherwise, the legislative intent to ensure public safety could easily be circumvented if the owner claims that the responsibility for gondola maintenance lies with an independent contractor and therefore should not be held liable, and vice versa.

4. Constitutionality and human rights considerations: the Court must be satisfied that the reverse onus has a rational connection with the pursuit of a legitimate aim and that it is no more than necessary for the achievement of that aim. If those tests are met, the Court must be satisfied overall that the adoption of a reverse onus strikes a reasonable balance between the societal benefits promoted and the inroads made into the constitutionally protected presumption of innocence.

If, upon interpreting the statutes, the presumption of mens rea is displaced, three possible alternatives arose under Hong Kong law, namely whether the legislative intent was:

1. to allow a defence if the defendant can prove on the balance of probabilities that the prohibited act is done in the honest and reasonable belief that the circumstances are such that, if true, he would not be guilty of the offence; or 
2. to confine the defences open to the accused in relation to his mental state to the statutory defences expressly provided for in relation to the offence charged; or 
3. to make the offence one of absolute liability so that the prosecution succeeds if the accused is proved to have performed or brought about the actus reus, regardless of his state of mind.