The law of evidence refers to the materials which may be produced in open court to prove that the defendant has, or has not, committed the offence in question. Although in theory (ie in the substantive law), a defendant may appear to be liable for a criminal offence, whether such liability is proven in practice will ultimately depend on the evidence available, the use of that evidence and how the arbiters of fact treat that particular evidence. For a thorough account of the law of evidence, see Doak, McGourlay and Thomas, Evidence: Law and Context, 5th edn (Routledge, 2018).
1.7.2.1 Principles of evidence
The rules of evidence are predicated on a number of core principles that apply to most forms of evidence. These core principles are detailed in Table 1.4.
Table 1.4Core principles of evidence
| Core principle | Explanation |
| Admissibility | The admissibility of evidence is a matter for the arbiter of law, ie the judge or magistrates. In R v Terry [1996] 2 SCR 207 (Canada) it was held that evidence will be admissible if: (a)it is relevant; (b)such that a jury, properly warned about any defects it might have, could place some weight on it; and (c)it is not excluded by any rule of law. |
| Relevance | The relevance of evidence is also a matter to be determined by the arbiter of law. According to Lord Simon in DPP v Kilbourne [1973] AC 729, evidence is relevant if ‘it is logically probative or disprobative of some matter which requires proof’. This essentially means that if the evidence goes to prove or disprove a particular matter in issue between the parties, it is considered as being relevant. |
| Weight | The weight of the evidence is a matter for the arbiters of fact; it is their role to determine how much weight they wish to afford to a particular piece of evidence. Like relevance, weight is a question of degree and ultimately depends on how the arbiters of fact view the usefulness of the evidence. At one end of the spectrum, the evidence may be of little probative value, being so weak that it is described as ‘insufficient evidence’, whereas, at the other end, it may be virtually conclusive of the facts in issue that it is described as ‘prima facie evidence’. |
The use of these principles ultimately depends upon the matter which is sought to be proven/disproven. In this respect, there are two matters that are relevant to the law of evidence:
(a) Facts in issue: These are the facts that are at the centre of a criminal trial and refer to the issue being contested between the parties. In a crime where the defendant pleads not guilty on account that he did not commit the offence, every element of that offence therefore becomes a fact in issue – ie whether the defendant committed each element is in contention. In a similar vein, where a defendant pleads not guilty on account of one element of an offence (eg that a complainant did consent to sexual intercourse), then the only fact in issue relevant to this case is whether the complainant consented or not. Every other issue, ie whether there has been an act of sexual intercourse, is therefore irrelevant.
(b)Collateral facts: These are facts that do not form part of the facts in issue. These facts are relevant in terms of the reliability of witnesses and the evidence produced. Counsel will often cross-examine a witness regarding their evidence in an attempt to discredit them, eg by suggesting that they are mistaken or, potentially, lying.
1.7.2.2 Types of evidence
There are a number of different forms of evidence that may be admitted in a criminal trial that go towards proving a fact in issue or collateral fact. These forms can be divided into a number of different categories:
Table 1.5Types of evidence (explained )
| Type of evidence | Explanation |
| Direct | This refers to evidence that is ‘first hand’, meaning that the witness who is communicating the evidence, either orally at trial (known as ‘live evidence’) or through a witness statement, witnessed the event personally. The witness may have evidence that relates to what they saw, heard, felt, smelt or tasted (ie their five senses). Such evidence is the most important and persuasive. An example could be that Jack saw Jill in an alleyway committing a murder. |
| Indirect | More often referred to as ‘hearsay’ evidence, this is admitted evidence that is not a direct testimony of what the witness saw or heard; rather, hearsay evidence concerns information that the witness was informed of by another. An example could be that Jack was told by Andy that he saw Jill in the alleyway where the murder was committed on the night of the murder, and Jack relays this information to the court because Andy is unable to do so for some reason. |
| Documentary | This refers to any evidence that is not produced in open court by live testimony. Such matters as witness statements, police interview records, CCTV recordings, etc all amount to documentary evidence. An example could be that the nightclub which is next to the alleyway has a CCTV recording of the alleyway showing Jill committing the offence. |
| Circumstantial | This refers to evidence that is neither direct nor hearsay, but rather goes to prove, by inference, a particular fact in issue. The focus on such evidence, therefore, is on the inference that may be drawn by the presence of such evidence. An example could be that Jack saw Jill running from the alleyway where the murder was committed. |
| Real | This refers to the physical objects relevant to the criminal offence, eg a knife or a gun. Such evidence is useful but only where it is used or considered alongside other evidence. An example could be that the police recover a knife from the alleyway where the murder was committed, Jack says that he saw Jill with the knife and it is discovered that Jill’s fingerprints are on the knife. |
| Expert | This refers to the evidence given by an expert in relation to a matter that requires clarification or detailed knowledge in that area. An expert may be required to explain how a gun works, or whether the defendant is suffering from insanity, etc. An example could be that expert evidence is admitted to explain the presence of Jill’s fingerprints on the knife. |
1.7.2.3Burden and standard of proof
Burden of proof
In criminal cases, the fundamental principle is that the prosecution bears the burden of proving that the defendant committed the offence in question. This fundamental principle is known as the ‘golden rule’ and was emphasised by the House of Lords in Woolmington v DPP [1935] AC 462, where Viscount Sankey famously stated:
Throughout the web of English criminal law one golden thread is always to be seen, that it is the duty of the prosecution to prove the prisoner’s guilt.
This principle is reinforced by Article 6(2) of the ECHR which prescribes that an individual is to be considered innocent until proven guilty. There are, however, exceptions to the principle that the prosecution bears the burden of proof. Before we consider these, however, it is first necessary to explain what burdens of proof exist. Two burdens of proof exist, namely:
• the legal (persuasive) burden; and
•