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Mandatory alcohol interlock scheme

Drivers who commit serious drink drive offences must have an alcohol interlock device fitted to their vehicle for a time equal to their disqualification. The mandatory alcohol interlock scheme applies after the disqualification period has been served.

The following offences are classified as serious drink driving offences for which the mandatory interlock scheme applies:

  • A second or subsequent offence of driving with a blood alcohol reading above 0.08 (i.e. category 2 offence)
  • Driving with a blood alcohol reading at or above 0.15 (i.e. category 3 offence)
  • Refusing to provide a breath or blood sample for alcohol testing
  • Driving under the influence

[Motor Vehicles Act 1959 (SA) s 81E]

In determining whether an offence of driving with a blood alcohol reading above 0.08 (category 2 offence) is a second offence for the purposes of assessing whether the mandatory interlock scheme applies, any previous drink driving offencs (other than category 1 offences) will be taken into account but only if the previous offence was committed within the 5 year period immediately preceding the date of the category 2 offence.

The cost of fitting of the alcohol interlock device will be the responsibility of the driver but a concession scheme will be available to eligible concession card holders.

Conditions of mandatory interlock scheme

  • Driver must not drive any other motor vehicle than that nominated to the Registrar to be fitted with alcohol interlock device
  • Driver must not drive nominated vehicle unless it has been fitted with a properly functioning alcohol interlock device that has been installed by an approved alcohol interlock provider
  • Driver must not interfere with the alcohol interlock device or cause or permit the device to be interfered with
  • Driver must carry certificate certifying that the alcohol interlock fitted to the vehicle was properly functioning when last examined by approved alcohol interlock provider
  • Driver must produce certificate for inspection when required to do so by a police officer
  • Driver must provide nominated vehicle for inspection by an approved alcohol interlock provider if served by written notice by Registrar

[Motor Vehicles Act 1959 (SA) s 81F].

Drivers required to enter into the mandatory interlock scheme are exempt from the requirement to undergo a drug or alcohol dependency assessment pursuant to section 79B of the Motor Vehicles Act 1959 (SA).


It is an offence to contravene any of the conditions of the mandatory interlock scheme [s 81H].

Maximum penalty: $2500

It is an offence to assist the holder of a licence subject to the mandatory interlock scheme to contravene the conditions [s 81H].

Maximum penalty: $2500

Driving without a licence having committed a serious drink drive offence [s 74(2A)].

Maximum penalty: $5000 or 1 year imprisonment

See further: the Department of Planning, Transport and Infrastructure's webpage and brochure on the Mandantory Alcohol Interlock Scheme.

Alcohol, tobacco and other drugs  :  Last Revised: Mon Feb 5th 2018
The content of the Law Handbook is made available as a public service for information purposes only and should not be relied upon as a substitute for legal advice. See Disclaimer for details. For free and confidential legal advice in South Australia call 1300 366 424.