ZONDI AJ [61] Section 39(1)(b) of the Constitution enjoins a court to consider these instruments when interpreting the Bill of Rights.47 Whether the declaration of constitutional invalidity will affect the right to a fair trial of an accused implicated in offences that occurred more than 20 years earlier [62] Section 35(3)(l) of the Constitution recognises the principle of legality, namely that the accused may not be found guilty of a crime unless the type of conduct with which he or she is charged was recognised by the law as a crime at the time it was committed. This Court in Masiya applied this principle when it set aside the conviction for rape imposed by the Regional Court and replaced it with one of indecent assault. This Court stated the following: ―Section 35(3)(l) of the Constitution confirms a long-standing principle of the common law that provides that accused persons may not be convicted of offences where the conduct for which they are charged did not constitute an offence at the time it was committed. Although at first blush this provision might not seem to be implicated by finding Mr Masiya guilty of rape in this case, because the act he committed did constitute an offence both under national law and international law at the time he committed it, in my view, the jurisprudence of this Court would suggest otherwise. ... The strong view of legality adopted in Veldman suggests that it would be unfair to convict Mr Masiya of an offence in circumstances where the conduct in question did not constitute the offence at the time of the commission. I conclude so despite the fact that his conduct is a crime that evokes exceptionally strong emotions from many quarters of society. However, a development that is necessary to clarify the law should not be to the detriment of the accused person concerned unless he was aware of the nature of the criminality of his act. In this case, it can hardly be said that Mr Masiya was indeed aware, foresaw or ought reasonably to have foreseen that his act might constitute rape as the magistrate appears to suggest. The parameters of the trial were known to all parties before the Court and the trial was prosecuted, pleaded and defended on those bases. It follows therefore that he cannot and should not bear adverse 47 S v Baloyi [1999] ZACC 19; 2000 (2) SA 425 (CC); 2000 (1) BCLR 86 (CC) at para 13. 26