Section 20 of the Drugs and Drugs Trafficking Act 140 of 1992, which creates a reverse onus by presuming possession of drugs found in the immediate vicinity of an accused until the contrary is proved, is constitutionally invalid. Such a provision, which requires facts essential to prosecution to be presumed even where there is reasonable doubt, violates the constitutional rights of accused persons under section 35(3)(h) of the 1996 Constitution.