that it is now widely recognised that the expression "prescribed by law", when used in a context such as art. 39 of the Basic Law, mandates the principle of legal certainty." In that case, the Court of Final Appeal laid down two requirements for legal certainty: The relevant law must be sufficiently certain and precise to enable citizens to regulate his conduct The relevant law must be adequately accessible The Court remarked that a balance has to be struck between requiring the law to be formulated with sufficient precision and the desirability of avoiding rigidity in the law. The precision required will vary according to the context of the law; if it is impossible to formulate the law with absolute certainty, a description of the nature of the activity will provide sufficient notice. On the facts of that case, the Court held that the common law offence of misconduct in a public office was sufficiently certain. Presumption of innocence Article 87 of the Basic Law and Article 11 of the Bill of Rights provides that anyone charged with a criminal offence shall have the right to be presumed innocent until proven guilty according to law. This presumption is well established under the common law; the much-celebrated case of Woolmington v DPP laid down the basic criminal law principle that it is the duty of the prosecution to prove the defendant's guilt subject to the defence of insanity and statutory exceptions. If, at the end of and on the whole of the case, there is a reasonable doubt as to whether the defendant committed the criminal offence in question, the prosecution has not made out the case and the defendant is entitled to an acquittal. However, as mentioned above, statutes may place the burden of proof on the defendant or make presumptions of facts which require the defendant to prove otherwise. In such circumstances, the reverse burden must be justifiable to avoid being struck down as unconstitutional. According to R v. Sin Yau Ming, a statutory provision is prima facie unconstitutional if the defendant has to prove the essential elements of the offence. Moreover, the reverse burden must be justified under the Oakes test. This principle was partly affirmed by the Privy Council decision in AG v. Lee Kwong Kut when Lord Woolf said: Right to property The right to property is protected by Article 6 of the Basic Law. Furthermore,