The Land Transport Amendment Act 2009 (LTAA), which came into force on 1 November, allows Police to better detect drug drivers and charge them with the offence of ‘driving while impaired and with blood that contains evidence of use of a controlled drug or prescription medicine’. Let’s look a little more closely at how the system will work.

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There are three steps Police must follow before charging someone with ‘driving while impaired and with blood that contains evidence of use of a controlled drug or prescription medicine’.

1. Good cause to suspect
An officer must have a good reason to suspect that a driver has consumed a drug or drugs before they can test for drug impairment. Swerving across lanes, erratic driving or a driver’s personal demeanour might give them good cause to suspect that a driver has consumed something they shouldn’t have.

2. Unsatisfactory completion of a compulsory impairment test (CIT)
Once an officer has established good cause to suspect the driver has consumed a drug or drugs, the driver will be breath tested for alcohol to rule out drink driving as the cause of impairment. Good cause to suspect might also be established after a driver is pulled over for suspected drink driving but passes a breath test. In practice, Police will not progress to a CIT for drivers who fail a breath alcohol test, as the primary goal of removing an impaired driver from the road will have been achieved.

If a driver passes a breath test, the officer can then require them to undergo the CIT. The CIT consists of three behavioural tests that check whether a driver is impaired.

The first test is called the ‘walk and turn’. The driver must take a number of heel-to-toe steps along a straight line, then turn and repeat the steps in the opposite direction.

There are eight signs of impairment in this task: losing balance at the start of the test, starting the test before instructions have been completed, stepping off the line, not touching heel to toe, using arms to maintain balance, improper turn (not as demonstrated), stopping mid-test and taking the wrong number of steps. Exhibiting two or more of these signs of impairment constitutes failure to complete the test to the satisfaction of an officer.

The second test is called the ‘one leg stand’. This requires the driver to stand on one leg with the other leg raised in front of them. The driver must then count to from 1,000 to 1,030.

There are four signs of impairment for this test: placing the raised foot on the ground, hopping, swaying and using arms to balance. The driver fails to satisfactorily complete the test if they exhibit two or more of these signs of impairment or if they place their raised foot on the ground more than three times.

The final test involves assessing the driver’s pupil size and responsiveness. One example of this sort of test is called ‘gaze nystagmus’ and is conducted once for each eye. It requires the driver to focus on an object in front of their face and track its movement. An impaired driver will have trouble following the object, drifting off target then suddenly jumping back on target again. The inability to smoothly follow the target is called ‘nystagmus’ and constitutes failure of the test.

Additional eye tests will assess the size of the driver’s pupils, as different drugs can cause the pupils to dilate or constrict.

The CIT is not a straightforward pass/fail test; rather, it must be completed to the satisfaction of the officer administering it. If there are environmental factors that might influence a driver’s ability to complete the test, such as bad weather, being stopped on a busy motorway or poor light, the officer can require the driver to accompany them to a more suitable location.

If a driver refuses to complete the test, they can be charged with refusing the CIT, which carries the same penalties as an impaired driving offence. If a driver fails to complete the CIT to the satisfaction of the officer, they will be required to provide a blood sample and will be forbidden to drive for a number of hours.

3. The presence of a drug or drugs in a blood sample
Drivers who do not satisfactorily complete the CIT will be required to undergo an evidential blood test. The presence of a drug or drugs in the blood in any amount will result in a charge of ‘driving while impaired and with blood that contains evidence of use of a controlled drug or prescription medicine’.

Blood results will not be available immediately and may take up to four weeks to process. For this reason, unsatisfactory completion of the CIT alone is enough to forbid a driver from driving for a number of hours to enable the impairing effects of the drug to wear off. This achieves the immediate road safety objective of removing the impaired driver from the road. However, a driver cannot be charged with a drug driving offence unless there is also evidence of the presence of a drug or drugs in the blood sample.

Random roadside drug testing is not allowed under the LTAA 2009, primarily because the technology does not yet exist to allow for quick and accurate testing. Saliva testing is growing in popularity overseas, but current saliva testing kits are time-consuming to administer and not sufficiently reliable to be used in a criminal justice application.

Saliva tests will only show the presence of a drug in the specimen, which does not necessarily equate to impairment.

Additional information about the new law can be found on the Ministry of Transport website.