Government has tabled amendments to give drunk drivers a guaranteed period of disqualification.The Traffic Offences (Penalties) Amendment Act 2013 imposes an obligatory 18-month period of disqualification on the first offence of driving while impaired, driving while over the legal blood-alcohol limit of 80mg of alcohol in 100ml of blood and refusing to submit to a breath test.A second offence carries an obligatory three-year disqualification, while any subsequent offences carry a five-year period of disqualification.The amendment also includes another offence — driving a motor car, auxiliary bicycle, cycle, or any other vehicle other than a motor car while under the influence of a dangerous drug.The offence carries the same penalty as driving while impaired by alcohol, with repeat offenders facing fines of up to $5,000, a period of disqualification up to five years and as many as 12 traffic points.Offenders are also potentially subject to a period of imprisonment for up to a year on the first offence, 18 months on the second offence and two years for subsequent offences.The legislation is intended to fix an error in previous amendment to the act. While the earlier amendments increased the maximum penalty for drink-driving offences, it failed to state that periods of disqualification were mandatory.As a result, magistrates have been using their own discretion in recent month, sparing some offenders a period of disqualification if they find such a penalty would be disproportionate — typically when defendants would lose the ability to work due to the disqualification.