Driving tests

Alcohol and drug limits when driving

beer-glassAlcohol and many drugs reduce your reaction time and change your perception of what’s going on around you. This is what makes them dangerous when driving. You dramatically increase the risk of killing or seriously injuring another person (and yourself) by driving under the influence of alcohol and/or drugs. In this article we’ll tell you the current limits for driving after drinking based on your age, and what processes you will be asked to go through if you are pulled over under suspicion of driving under the influence.

Can you calculate your blood alcohol level?

It is impossible to calculate your blood alcohol level because it relies on too many factors:

  • Your age
  • Your gender
  • Your weight
  • Your liver’s ability to process the alcohol
  • Your overall fitness, fatigue and general health
  • How much you have eaten
  • How recently you have eaten
  • The relative concentration of alcohol in the drink you are drinking
  • The amount you have drunk

Plus, your blood alcohol level can continue to increase for up to two hours after you have stopped drinking.

Driving after drinking alcohol: what are the limits

Blood alcohol is measured in micrograms per litre of breath or milligrams per 100ml of blood. The law gives limits for these amounts based on your age.

16-19 years old

If you are under twenty the legal limit is zero. This means it’s safest not to have anything to drink before you drive as even a small drink could register in your blood. If you are caught with a level between 30-150mcg per litre of breath you could be fined and given 50 demerit points. If you drive with more than 150mcg per litre of blood then you could be fined $2250, sent to prison for up to 3 months, be disqualified from driving for at least 3 months, and get 50 demerit points.

20+ years old

The legal limit is 250mcg per litre of breath or 50mg per 100ml of blood as of 1 December 2014. There’s no definitive rule as to how many drinks you can have before you reach these limits. If you are a 50kg woman drinking on an empty stomach you will reach these limits very quickly; if you are a 100kg man that’s just eaten a full meal, it will be more.

To be safe, though, don’t drink any alcohol and drive because any amount of alcohol (however small) has some effect on your reactions, and therefore your driving. Choose a friend who hasn’t been drinking, or a taxi, or dial-a-driver.

Driving after taking drugs

There are many different types of drugs you can take, some of which are legal and others which are illegal. The law is clear in that it says if you have taken a drug that affects your driving ability, then you should not drive. This includes some drugs prescribed by doctors. Your doctor can tell you if it’s safe to drive after taking one of these drugs.

Testing for the presence of alcohol and/or drugs

The police can stop you and breath test you at any time using one of the following tests:

  1. Passive breath test: you will be asked to talk into a hand-held device in front of your mount. This shows if you have recently drunk alcohol. If it registers alcohol you will have to take a breath screening test.
  2. Breath screening test: you will be asked to blow into an electronic device which will give a reading for breath alcohol. If it’s high you will need to give an evidential breath sample
  3. Evidential breath test: this electronic device is precisely calibrated to measure breath-alcohol and its result can be used as evidence in court.
  4. Blood test: you may opt to take, or may be instructed to take a blood test in which a medical doctor will test for alcohol and drugs.

If you are suspected of drinking and driving or you’re signalled to stop at a police checkpoint you can be asked to take a passive breath test, which is the first step. The device will give a result almost immediately and you must wait until the officer has sighted the result and either tells you you can go or indicates that you will need a breath screening test or blood test. In this case, you will need to hand over the keys to your vehicle (if asked by the officer), go with them if required, and agree to a blood test.

Compulsory drug impairment test

The test includes an eye assessment, walk and turn and standing on one leg. If you fail you may be required to have a blood test and will be forbidden to drive.

The compulsory impairment test can be required if the police officer has good cause to suspect you’re driving while impaired by a drug or drugs.

What are my rights if I’m stopped for drink driving?

You can refuse an evidential breath test or the blood test, but not both – you must consent to at least one of them and it is an offence not to do so, i.e. you will be arrested and may be fined.

If the evidential breath test shows you are over the limit then you can request a blood test.

You may talk to a lawyer before you have an evidential breath or blood test, and a telephone will be made available to you for this purpose. You may also request an independent analysis of the sample, but it’s important that you talk to a lawyer before requesting this.

What are the penalties if I’m stopped for drink driving?

Roadside (on-the-spot) licence suspension

You will receive an immediate suspension if your test reading is greater than 130mg/100ml of blood or 650mcg/litre of breath if you have no previous convictions. If you have a previous conviction this limit is 80mg or 400mcg if you’ve been convicted of driving or attempting to drive under the influence or with excess breath or blood alcohol, failing to consent to a blood sample, or causing death or injury while driving under the influence.

The immediate suspension is 28 days, plus you will have to face court-imposed penalties as listed below.

Court-imposed penalties for alcohol and drugs offences

Offence Amount of alcohol Penalty
Blood Breath Prison Fine Disqualification or suspension of licence
Fail an evidential breath test n/a 251-400mcg of alcohol per litre of breath None $200 + 50 demerit None, unless you exceed max demerit points.
Fail blood test result 51-80mg per 100ml n/a None $700 + 50 demerit None, unless you exceed max demerit points. Total costs may vary
You kill or injure someone when driving after drinking too much or taking drugs More than 80mg per 100ml More than 400mcg per litre Up to 10 years Up to $20,000 First or second offence – one year or more, third or subsequent offence – more than one year
You drive, or try to drive, after drinking too much or taking drugs More than 80mg per 100ml More than 400mcg per litre First and second offences
Up to three months Up to $4500 Six months or more
Third and subsequent offences
Up to two years Up to $6000 More than one year
You drive, or try to drive, after drinking too much More than
80mg per 100ml
More than
400mcg per litre
Second and subsequent offences
The court may impose a zero alcohol licence in addition to the penalties listed above.
You drive, or try to drive, after drinking too much More than
160mg per 100ml
More than
800mcg per litre
First and subsequent offences
The court may impose an alcohol interlock disqualification with an accompanying three months disqualification period as an alternative to the penalties listed below.
You drive, or try to drive, after drinking too much or taking drugs and you are aged under 20 years More than 30mg per 100ml More than 150mcg per litre Up to three months Up to $2250 Three months or more
You refuse to give blood when asked by a police officer, doctor or approved person First and second offence
Up to three months Up to $4500 Six months or more
Third and subsequent offences
Up to two years Up to $6000 More than one year
You refuse to go with a police officer for an evidential breath test or blood test Up to $4500 As decided by the court
You are in charge of a vehicle after drinking too much or taking drugs and you do not hand over the keys when asked by a police officer Up to $10,000

Penalties for drug impaired driving or driving with class A drugs in the blood stream

Offence Penalty
Prison Fine Disqualification or suspension of licence
You drive drug impaired but no one is injured, or fail or refuse to do the impairment test First or second offence
Up to three months Up to $4500 At least six months
Third or subsequent offence
Up to two years Up to $6000 More than one year
You drive drug impaired causing injury or death Up to three years Up to $10,000 One year or more
You drive carelessly causing injury or death with Class A drugs in the blood Up to three years Up to $10,000 One year or more

Repeat offenders

The courts take a dim view on repeat offenders and will increase penalties substantially if you are caught a second or subsequent time. There are also other penalties if you are caught again within a five-year period of being convicted of an alcohol related offence and one of those offences involves:

  • having a blood-alcohol level of more than 200mg/100ml or a breath alcohol level of more than 1000mcg per litre of breath
  • driving under the influence of alcohol or drugs
  • refusing to either give a breath or blood sample or go with a police officer

You will be disqualified for an indefinite period of time and be required to attend a Ministry of Health alcohol assessment centre.

If you commit an alcohol-related offence and your breath or blood alcohol levels are over twice the limit and you’ve already been convicted of a previous offence within a 5-year period then you could be given an alcohol interlock disqualification and 3-month disqualification or given a zero alcohol disqualification.

driver training

Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers’ Guild

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Posted in Advice, Car, Heavy Vehicle, Motorbike
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