You suspect the breathalyser had malfuntioned as what you consumed does not reflect the extraordinary high reading on the breath testing instrument.  Do you or the prosecution bear the onus of establishing that the breathalyser was or was not working?

The case of DPP v Luff [2006] VSC 195 confirmed that the onus of establishing that the breathalyser was not working or had malfunctioned at the relevant time of the test is one the defendant must discharge under section 49(4) of the Road Safety Act 1986.  To successfully use this defence the Court (usually a Magistrate) must be satisfied on the balance of probabilities that the instrument was not working, or had not been operated correctly.  it is not an element of an offence under s. 49(1)(f) for the prosecution to prove specifically that the breathalyser was used in conformity with the prescribed regulations, or correctly by the operator.