Under s 98A(3) of the Road Traffic Act 1974 (WA), evidence from speed measuring equipment is prima facie evidence of the speed of the vehicle, not merely evidence that the machine registered a particular reading. Once that prima facie evidence is adduced, the evidentiary burden shifts to the defence to adduce evidence capable of displacing it. The prosecution is not required to call expert evidence to support the accuracy of the machine, and counsel's questions in cross-examination do not constitute evidence. Section 24 of the Criminal Code (WA) (mistake of fact) can only become relevant after the prosecution evidence of speed has been accepted. Whether s 24 applies to speeding offences at all remains an open question in Western Australia.
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