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Over the limit defences

Information about some of the defences that have been used when someone is charged with being over the limit.

Below are summaries of some defences that have been used to argue against a drink driving charge when the driver is charged with exceeding the prescribed limit.

Driver advised not to take blood test

A driver was advised by a breath test operator that a blood test would give a higher reading after analysing the driver’s breath. The breath analysis showed a BAC of 0.074. Because of this advice, the driver did not ask to have a blood test. The magistrate used their discretion to exclude the reading on the certificate for breath analysis and dismissed the charge. Appeal upheld.

See DPP v Moore [2002] VSC 29 (27 February 2002)(opens in a new window).

Police decided driver unable to give breath sample

After a driver gave a preliminary breath sample which detected alcohol on their breath, the police sergeant decided that the driver was incapable of furnishing a sample of breath for analysis due to a medical condition and organised for a blood sample to be taken instead.

Both the prosecutor and the County Court judge agreed that proper procedure had not been followed (according to s. 55(9A)), but the judge decided to allow the evidence and the driver was convicted.

Held: Requirement under s. 55 for a driver to allow a medical practitioner to take blood was not an element essential or an essential pre-condition to be proved by the prosecution before a s. 49(1)(g) (over the limit within 3 hours according to a blood sample analysis) offence could be established.

See McPherson v County Court [2003] VSC 105 (4 April 2003)(opens in a new window).

Police breaching service requirements

At first instance the magistrate found the driver guilty and convicted them of a s. 49(1)(g) offence, despite the prosecution failing to make sure that documents had been properly served. The blood sample certificate had not been properly served on the driver. Time for service is:

  • at least 10 days before the court mention date for the certificate, and
  • least 14 days before the mention date for charge and summons.

Appeal allowed (Platz v Bramby [2002] VSC)).

Section 57(9) gives a driver the choice of asking for a blood sample. If a driver is not given an informed choice then evidence of the result could not be tendered as evidence. Circumstances were that more than 3 hours had passed since time of driving and yet the driver was under impression that they had no choice but to provide a blood sample.

Held: Driver must be given informed consent (Day v County Court & Anor [2002] VSC 426).

Difficulty proving that breathalyser not working properly

For the offence of driving with more than prescribed amount of alcohol in the breath or blood (s. 49(1)(b)) there is no obligation on the prosecution to prove that the breathalyser device was operating properly. However, if reasonable doubt exists about the reliability of an instrument the magistrate may not be satisfied that an offence was committed. In this case the prosecution failed to establish an element of s. 49(1)(b) offence which was essential to a conviction.

However, for a s. 49(1)(f) (fail the test) offence there is an explicit reversal of onus of proof, meaning that legislature intended that the results from breath analysing instrument are to be taken as accurate unless the driver can prove on balance of probabilities that the machine was not operating properly. The driver's appeal dismissed.

See Luff v DPP [2003] VSCA 81 (24 June 2003)(opens in a new window).

Rise and fall or reconstruction of drinking arguments

The first defence involves arguments related to the time of the last drink, the time of driving and of testing. This argument involves an expert coming to give evidence about the physiology of alcohol in person's bloodstream. It usually rises for between 40 and 60 minutes after the person stops drinking. Depending on the time of testing, if the person was tested within this time, they could argue that their BAC at the time of driving was lower than at the time of reading.

The reconstruction argument involves the defendant and other witnesses giving evidence on the amount of alcohol consumed over a period and an expert then giving evidence as to the absorption and elimination rates of alcohol as it moves through a person's body. The expert would give an opinion of the person's BAC at the time of testing to allege that the reading was not correct and could not be relied on.

See [5610.193] in Motor & traffic law—Victoria(opens in a new window).

More information


Road Safety Act 1986 (Vic)

  • s. 57(5)—time limit for serving blood test analysis certificate

See Road Safety Act 1986 (Vic)(opens in a new window).

Magistrates' Court Act 1989 (Vic)

  • s. 34(1)(a)(ii)—time limit for summons to answer charge

See Magistrates' Court Act 1989 (Vic)(opens in a new window).


See ‘What blood alcohol reading is my client's blood sample?’ by David McSteen (Law Institute Journal, April 2006, pp. 62-3) for tips about contesting the blood alcohol reading certificate—particularly where reading is .07 or .05.

Motor & Traffic Law—Victoria

Lexis Nexus's Motor & Traffic law has detailed commentary about drink driving defences.

  • Wording of charge [5610.135]
  • Material facts relevant to prosecution of charge [5610.140]
  • Defences [5610.193]

Note: To access content type the brackets and number reference into the search box, for example "[5610.105]''

See Defences [5610.193] in Part 5—Offences involving alcohol or other drugs [5600](opens in a new window).