Defending a Drink Driving Charge

• How can I defend a drink driving charge?
• Can I fight a drink driving charge?
• I blew over so I must be guilty, right?
• Should I just accept a breath test result?
• Why get a lawyer for a drink driving charge?
• Can a blood test disprove a breath analysis result?
• Can I prove my own elimination rate?
• What if I have been drinking after I stopped driving?
• Can police require someone who isn’t driving to submit a breath analysis?
• How are blood tests used to prove drink driving?

How can I defend a drink driving charge?

Many people think that the very fact that they have been charged with drink driving, there is no choice but to plead and accept the harsh drink driving penalties that will result. The fact is that this is not the case. For anyone charged with drink driving, there is good reason to investigate whether they have a defence to the charge. This is because of the way the law relating to drink driving works and how the results of a breath analysis test are used to prove a person’s blood alcohol concentration (or BAC) at the time of driving. The fact is that not everyone charged with drink driving was necessarily over the limit.

Can I fight a drink driving charge?

The answer is ‘yes’. Anyone who has been charged with drink driving needs to understand how a breath analysis test result or blood test result is used to prove their blood alcohol concentration at the time they were driving. This is a complex area of law that requires a real understanding of various legal and procedural issues and the best thing to do is to speak with a specialist traffic lawyer before making any decision. If you want to know more, there’s a lot to unpack so here is some of the basic information as to the issues involved in defending a drink driving charge.

I Blew Over So I Must Be Guilty – Right?

The law relating to drink driving is complex and requires a thorough understanding of all of the evidentiary provisions that apply in order to identify whether a defence exists or if police have sufficient evidence to prove their case. What’s important to understand is that very rarely will a person be convicted of drink driving on the basis of a BAC that truly reflected the amount of alcohol that was in their system at the time they were driving.

Blood alcohol levels change over time.

The reason for this is that a person’s blood alcohol concentration is dynamic and so it changes over time. As alcohol is consumed, it is absorbed into your system and over time your blood alcohol level increases. Similarly, over time, your body metabolizes that alcohol. As you continue to ingest alcohol, your blood alcohol level is increasing. When you stop drinking, it will continue to increase as you absorb the last of the alcohol you consumed, reach a peak, and then go down as you continue to metabolise the alcohol and eradicate it from your system. For this reason, police can almost never prove what a person’s blood alcohol concentration was at the time of driving. From the very moment that they are stopped by police, the concentration of alcohol in their blood will be changing.  

Should I Just Accept a Breath Test Result? What Does a Breath Analysis Prove?

To help police to prove these types of charges, the law creates what is described as a ‘legal fiction’, namely that provided certain requirements and procedures are complied with when a breath analysis is conducted, the results of the breath analysis will be regarded as being the person’s blood alcohol concentration for the preceding three hours. This means then that if the breath analysis is conducted within three hours of driving, then subject to certain requirements, the police can use the results of that test as proof that the person had that concentration of alcohol in their blood at the time of driving, even though that was not the case. In fact, for people who are driving shortly after they stopped drinking, their blood alcohol concentration will continue to increase between the time they have stopped and the time they are required to submit to the breath analysis.In one case the Court heard evidence from a forensic scientist that the driver’s BAC at the time of driving would have been less than the breath analysis result, but because that evidence did not actually dispute the outcome of the breath test itself the driver was still found guilty because of this legal presumption.

A breath analysis does not actually prove the BAC at the time of driving.

You might think then that it would be a good idea for the breath analysis to be conducted as quickly as possible. However, there’s the challenge, because the police are required to wait a specified period of time before conducting the breath analysis so as to ensure that there is no residual mouth alcohol that could affect the results of the test. In fact, the police have eight hours within which to conduct a breath analysis test and can’t be compelled to conduct the test sooner. So because there will almost always be a period of at least 20 minutes from when the person is stopped driving to when the breath test is conducted, there will be in very many cases a significant difference between the person’s true blood alcohol concentration at the time they were driving and the results of the breath analysis test. For this reason the Supreme Court has referred to this legal presumption as, ‘draconian,’ or in other words, ‘excessively harsh or severe.’

Why Get a Lawyer for a Drink Driving Charge?

A specialist traffic lawyer experienced in handling drink driving matters can review the evidence and determine whether the police have complied with all of the requirements and procedures relating to breath analyses and breath analysis tests. These include the manner in which the breath test is conducted, and whether various documents are delivered to the subject of the breath analysis test. If not, then police can’t rely on the presumption that the result of the breath analysis proves your BAC at the time of driving. So it is possible to defend drink driving charges, but it requires specialist knowledge of the area of law relating to drink driving matters.

Can a Blood Test Disprove Breath Analysis Results?

Many people wonder whether the results of an analysis of blood taken after the breath analysis test can disprove or rebut the results of the test. The law allows for a person who has been required to submit to a breath analysis to elect to have a sample of blood taken at their own expense in order to check the results of the breath analysis. If the driver requests that the breath analysis operator provide them with a blood test kit, they then take that kit to a medical practitioner or registered nurse to have the blood sample taken for independent analysis. However, for the very same reasons as stated previously, namely that a person’s BAC is constantly changing, just because the results of the blood test are different from the breath test does not automatically mean that the breath analysis reading is incorrect. It is necessary to prove that the results of the blood test demonstrate that the results of the breath analysis were exaggerated, or in other words, that the breath analysing instrument produced a reading that would have been significantly more than the person’s actual BAC at the time of the test. So simply because the blood sample analysis shows a BAC which is lower than the breath analysis, that doesn’t of itself mean that the breath analysis was exaggerated. The person may have been in the elimination stage of alcohol metabolism between the time of the breath analysis and the time the blood sample is taken, which means that their BAC would have been going down What’s necessary is to show that the difference between the two readings cannot merely be explained by the fact that the alcohol was being metabolised, because the difference is too great to be explained by that alone. It’s important for anyone who has been charged with drink driving and elected to have a blood sample taken to get advice from a lawyer with significant experience in these matters who will be able to provide advice as to how to obtain evidence, such as a report from a forensic pathologist, so as to determine whether the results of the blood analysis give rise to a defence to the charge.  

Can I Prove My Own Elimination Rate?

Rulings that the courts have made with regard to whether the difference between a breath analysis test and the results of a blood sample show that the breath analysis reading was exaggerated generally rely on expert evidence as to the range within which people generally eliminate alcohol from their system. However, each person is different in that regard and it is possible to obtain evidence to establish your own personal elimination rate. This involves undergoing supervised tests under controlled experimental conditions that provide absorption and elimination rates specifically related to the individual’s own metabolism. So a driver who has been charged with drink driving and obtained the results of a blood test can then review the difference between the two readings and the time period involved and effectively overlay their personal elimination rate in order to determine whether or not they are consistent or if the results of the blood test show that the breath test is exaggerated.

What if I Have Been Drinking After I Stopped Driving?

A further legal trap arises for people who consume alcohol after they’ve been driving. You might expect that if a person charged with drink driving can prove that they consumed alcohol after they were driving, then it wouldn’t be fair for the police to be able to rely upon the results of the breath analysis to prove their BAC at the time that they were driving by relying on the three hour presumption. However, that is not the case in South Australia.

A person who had no alcohol in their system when driving can still be convicted.

While it is possible to lead evidence of post driving drinking if it occurred more than three hours after the person was driving in order to overcome the statutory presumption, that is not the case if drinking occurs within the three hours after driving. In fact there is no opportunity whatsoever for a person who consumed alcohol within three hours of driving to challenge the presumption if they are subsequently required by police to submit to a breath analysis. This creates a situation where it is possible for a person who had no alcohol in their system when they were driving to be successfully prosecuted for drink driving.

Can Police Require Someone Who Isn’t Driving to Submit to a Breath Analysis?

In South Australia, police can require a person to submit to a breath analysis if they believe on reasonable grounds that a person is driving or has driven a motor vehicle. So it isn’t necessary for the person to be driving at the time the requirement is put to them. The only restriction is that the requirement can only be made up to eight (8) hours after they are believed to have been driving. Therefore, it is not uncommon for police who have received a report of a person driving or having been involved in an accident to require them to submit to a breath analysis even though they’re not driving at the time that the requirement is made. When that happens within three hours of driving, it doesn’t matter whether or not the person only consumed alcohol after they stopped driving, the result of the breath analysis can be used as proof that they were over the limit even if that wasn’t the case. It’s because of these legal complexities that it is critical to have an experienced specialist traffic lawyer to represent you if charged with a drink driving offence. It is simply not the case that because you blow into a breath analysing instrument and it produced a result that you are automatically guilty of drink driving, despite the perception that many have with regard to this type of charge.  

Other Ways to Challenge a Drink Driving Charge

A further important consideration relates to the way in which the police prove certain aspects of their case. As stated above, it is a requirement that the police follow all of the necessary procedures relating to breath analyses and the operation of breath analysing instruments in order to rely on the statutory three hour presumption that the results of the test can be used to establish the BAC at the time of driving. The law enables the police to rely on various certificates to prove important aspects of their case, such as the qualifications of the breath analysis operator to operate the instrument, or to establish that the BA instrument was operated correctly and that it was in proper working order. These certificates are also used to show that various legal requirements for the conduct of a breath analysis were followed by police. As the police are able to rely on these certificates to prove their case which effectively prevents the person charged challenging those matters, then in order for them to be admissible they must meet strict requirements of the law as to what’s contained in the certificates. This is where an experienced drink driving lawyer will be able to review these documents and identify any deficiencies contained within the certificates that would prevent their use or their intended purpose.

Police must meet strict requirements of the law

Most people would be surprised at the frequency with which breath analysis tests are not conducted according to the legal requirements or the certificates relied upon to prove essential aspects of the police case are deficient for one reason or another. Whether there is a defence available will depend upon the facts of each specific case. The fact is that with drink driving legislation, the situation is that a person is required to blow into a machine which produces a reading that is going to be relied upon to prove their BAC at the time of driving – when in fact that isn’t necessarily the case – and the person has no way of knowing whether the machine was operated correctly or whether it was in working order. It can’t be presumed that just because there are police involved that everything is being done as it should and experience has shown this is often not the case. There are many instances where the courts have been critical of the manner in which breath analysis tests have been conducted.

How Are Blood Tests Used to Prove Drink Driving?

While the majority of drink driving cases use the results of a breath analysis test as the basis to prove that the driver was over the limit, there are instances where a police will rely on the results of an analysis of the person’s blood instead. This is a very different situation as there are a number of ways in which police might obtain the results of a blood analysis after a person has been driving.

When a Blood Sample is Taken at Hospital

The most common circumstance is when a person has been involved in a car accident and they attend to the hospital for treatment in relation to injuries that they sustained in that accident. Any person aged 10 years or older who goes to a hospital for such treatment must have a sample of blood taken by the treating medical practitioner as soon as practicable, even if they are unconscious. It is possible for police to rely on the analysis of such a sample to prove a person’s BAC at the time of driving A similar presumption applies as with breath analysis samples, namely that the results of the analysis are to be taken to be the person’s BAC within the preceding three hours. Once again, however, that is subject to certain legal requirements being satisfied both with regard to the taking of the blood and the documents produced relating to the analysis.

Medical Condition Blood Samples

A different situation arises when a person who is required to submit to a breath analysis is unable to do so by reason of some physical or medical condition. In that case, they may request of the police officer that a sample of their blood is taken by a medical practitioner or registered nurse and the police must do all things reasonably necessary to facilitate the taking of that sample in those circumstances. The same presumption applies with regard to the results of the blood analysis and how they can be relied upon by police to prove the driver’s BAC at the time they were driving and these same issues need to be investigated in relation to potential defences.

Police Directed Blood Tests

In contrast to these, are situations where the police require a person to provide a blood sample which they are able to do in certain circumstances. Police can require a driver to submit to a blood test if they have already had the person submit to an alcotest (or roadside breath test). While this section is really intended to assist police to investigate drug driving charges, there is arguably no restriction on the use that police can make of the results of such a blood analysis. Nevertheless, the presumption that the results of the analysis may be used to prove the person’s BAC for the preceding three hours do not apply when a sample is taken pursuant to this power. Therefore, the results would only establish the person’s BAC at the time the blood sample was taken and it is necessary for police to prove what it would have been at the time of driving. This would be done by obtaining an expert report which is fraught with challenges because of the information that would be required for an expert to properly make this calculation.

It is vital to determine the circumstances under which the blood sample was obtained

It’s clear, therefore, that when police are relying on the results of the analysis of a sample of a person’s blood to prove a drink driving charge, it is vital to determine the circumstances under which the blood sample was provided or obtained and whether or not police can rely on any statutory presumption. Given the complexity that surrounds drink driving laws in South Australia it is clear that any person who is facing a drink driving charge should at the very least consult an experienced specialist traffic lawyer to determine their options. The penalties are significant, involving lengthy periods of licence disqualification and significant fines in addition to which there are other consequences, such as potentially the imposition of an interlock device in certain circumstances. If you are charged with a drink driving offence it is in your interests to contact a specialist traffic lawyer at Websters Lawyers on 8231 1363. We can provide you with some initial advice at no charge to assist in making a decision.