General Principles in Criminal Law

There are four important principles of the criminal law. These principles are set out briefly here and discussed more fully later in Class/forum.
Innocent until proven guilty
The basis of our system of criminal justice is that a person, although charged with an offence, is considered innocent until proved guilty of the offence. The magistrate, judge or jury, as the case may be, must be satisfied beyond a reasonable doubt that the person is guilty. Where there is a reasonable doubt, the person must be acquitted (that is, found to be not guilty of the offence).
Unfortunately, people sometimes think that a person who has been simply charged with an offence must therefore have committed the offence. The fact that a person has been charged does not mean that she or he is guilty, and any discussion of the charge should make it clear that at this stage the offence is only alleged.
Burden of proof
The task of proving the guilt of a defendant falls on the prosecution - it is not up to the defendant to establish her or his innocence. This rule applies in all criminal trials, although sometimes is up to the defendant to give evidence of a certain point in the defence case. For example, in those offences which prohibit a certain act 'without reasonable excuse', the defendant must explain her or his excuse, although it is up to the prosecution to prove that the excuse is not reasonable. In some cases the burden of proof of a particular defence (such as insanity) may be on the defendant, but then the defence need only be proved on the balance of probabilities, not beyond a reasonable doubt, as the prosecution must do.
Right to remain silent
While it is not entirely accurate to say that a person has a legal right to remain silent when questioned by the police, it is true to say that generally a person is not required to answer their questions. Legislation has created some exceptions to this rule. The main exception is that a police officer can request the name and address of a person found committing an offence, or who the police officer has reasonable cause to suspect has committed, or is about to commit, an offence or of a person who may be able to assist in the investigation of an offence or suspected offence [Summary Offences Act 1953 s.74A]. In these circumstances a person who refuses to give her or his name and address, or who gives a false name and address, commits an offence. Drivers of motor vehicles are also required to give their name and address, and that of the owner of the car, see : arrest and questioning.
Double jeopardy
The principle of criminal law called the double jeopardy rule is that no person should be punished more than once for the same offence and that no person ought to be placed twice in jeopardy (at risk) of being convicted. This means that a person who has been charged, tried and acquitted cannot be charged again for the same matter. However, often a new trial is ordered where for example, an appeal court overturns a conviction or where the first trial resulted in a hung jury or a mistrial.
Changes to the Criminal Law Consolidation Act 1935 mean that double jeopardy no longer applies for serious offences such as murder, manslaughter and aggravated rape, provided certain circumstances are met. There are two situations in which a person can be re-tried for an offence for which they have previously been acquitted:
• Where fresh and compelling evidence not provided at the original trial is produced. This evidence must be reliable and substantial.
OR
• Where the acquittal is shown to be a ‘tainted acquittal’. A tainted acquittal occurs where a person was not convicted of an offence because an administration of justice offence was committed (i.e. perjury, fabrication or concealment of evidence, bribery, witness or juror intimidation or attempting to pervert the course of justice). Charges can be laid against the acquitted person if it is more likely than not that they would have been convicted but for the administration of justice offence.