Section 117(4) of the Road Traffic (Administration) Act 2008 (WA) does not shift the legal onus of proof to the accused. The prosecution bears the onus of proving the speed of the vehicle beyond reasonable doubt at all times. Where there is evidence inconsistent with the speed ascertained by the equipment, the trier of fact must determine on the whole of the evidence whether the speed is proved beyond reasonable doubt. Davis v Armstrong and the line of cases following it should no longer be followed insofar as they held that the prima facie evidence provision shifted the onus to the accused to disprove the alleged speed on the balance of probabilities.
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