Introduction
In British, the phrase ‘the burden of proof’ has two meanings. Firstly, the risk of not persuading the jury and second the duty of going forward with the evidence to satisfy the judge. The presumption of innocence is the fundamental rule is criminal cases in which means the defendant is presumed to be innocent until proven guilty. There are in fact two different types of burden recognized by the law. These burdens are commonly known as legal burden and evidential burdens . A legal burden in criminal trials generally falls on prosecution to prove the elements of offence charged beyond reasonable doubt. This was decided by House Of Lords in the case of Woolmington v DPP .Here Viscount Sankey LC declared not the trial judge’s decision of reversing the burden of proving the defence on the accused was wrong and this burden should be borne by prosecution. Meanwhile, evidential burden is burden of adducing sufficient evidence to convince the judge there is an issue to put before court. This burdens is usually carried by the defendant to raise reasonable doubt by pointing to or adducing evidence in order to make his defence live issue. Once the defence is made, the prosecution must disprove the defence in order to prove their case beyond reasonable doubt. However it is doubtful how far it has had either effect, even after the Human Right Act 1998

Exceptions of the presumption
Through the web of English Criminal law, one golden threat is always to be seen that is duty of the prosecution to prove prisoners guilt. Viscount Sankey in Woolmington case referring in reverential terms to the golden thread while even the acknowledging two sets of exceptions one ,the defence of insanity based on the common law and other based on statute, either by express or implied provision. The first exception insanity to the Woolmington can be traced back to the advisory opinions of the judges in M’Naughten’s Case. Whenever the accused raises the insanity defence, therefore it is for him to establish on a balance of probabilities that at the time of the offence he was labouring under such defect of reason, from disease of mind, as not to know the nature and quality of his act or if he did know it, that he did not know he was doing what was wrong. However, it should be noted, in H v UK (1990) the European Court of Human Rights ruled that the insanity exception didn’t breach Art 6(2) since the rule didn’t concern the presumption of innocence, but the presumption of sanity.

Looking at the statutory exceptions to the reversal of legal burden , the accused will bear the legal burden if the parliament intends in statute. It can be either implied or express reversal of burden . All form of reversals will raise issue of compatibility with the presumption of innocence as stated in the Art 6 (2) of ECHR. Many statutes expressly impose a burden of proof on the accused to prove his case. When express statutory provision obliges accused to prove his defence, it will automatically swift a legal burden on him to prove his defence on the balance of probabilities without any assessment attached. It’s deemed regardless of the principle set down in Woolmington’s case.
In situation of implied reversals, the parliament tend to be silent as did not suggest who holds the burden. Therefore, the judges required to interpret Parliament’s intention by using various tools of interpretation. There are number of cases where an enactment may be constructed as impliedly imposing a legal burden on the accused. S101 of the Magistrates Courts Act 198013 lays down the general principle in respect of summary offences and where the statute does not expressly state who bears the legal burden . The effect of the section is that where the conduct of the accused creates an offence but in circumstances where the statute creates a defence in respect of an exception, exemption, proviso, excuse or qualification, the burden of proving of the defence will be placed on the accused. The principle originates partly from the notion that it is easy or easier for the accused to prove that he fall within the scope of defences because of the access to the relevant information . The problem with