Two 'easy' defences...

Drink & Drug Driving

  1. Breath test procedure
  2. Identification of the vehicle driver 
  3. Forensic evidence

A positive breath test, forensic evidence and a positive ID. Any chance of success?

My client was charged with three offences: driving with excess alcohol, failing to stop after an accident and failing to report an accident. My client’s car crashed into another vehicle. An eye witness apparently saw my client get out from the driver’s seat and run off. The witness called the police. My client was then arrested by the police about 15 minutes later in the location. He was breath tested and was over the limit.

My client had some cuts and bruising to his face, consistent with an air bag explosion. The police spoke to the eye witness who gave a description of my client. The police seized the car in order to test the airbag for DNA. The logic, of course, is that if the DNA matched my client then it would prove he was the driver at the time of the crash.

The police had a strong case. They had a positive breath test. They had an eye witness. They had forensic evidence. The police and CPS believed it was an open and shut case.

I represented this client from start to finish. You can’t imagine the surprise expressed by the CPS at the first court hearing when my client pleaded not guilty to all charges. The CPS solicitor looked at me like I was as mad as my client!

However, one thing I have learnt over the years is that it is vital to properly test the evidence. Just because the police or the CPS believe they have the evidence, it does not mean they have. Unless you accept the evidence and plead guilty, the CPS must prove the case based on accurate and reliable evidence to a standard beyond reasonable doubt.


When the police and CPS believe they have the right person, especially in circumstances such as in this case, I often find that the police and CPS fail to do what they should. My defence comprised three main elements:

  1. Accuracy of the breath test
  2. Identification of the driver
  3. Reliability of the forensic evidence

Let me briefly take you through each element of my defence.

Most solicitors fail to properly challenge breath test evidence (probably because most solicitors are not experts on drink-drive law). There is a belief that if a positive breath sample has been obtained then there is nothing to challenge. This is not the way I work. I always challenge every aspect of the breath test procedure - and you’ll be surprised just how often I find mistakes with the evidence.

Most people believe (including most solicitors) that if an intoxilyser printout has been obtained (from the breath test device) showing a reading over the limit then there is nothing to challenge. The printout must be right. Right?

- Wrong. The printout, by itself cannot be used on its own in evidence.

In every case, whilst completing a breath test, the police should complete a very detailed pro-forma known as the MGDDA document. This stands for Manual Guidance Drink Driving form A. It is about 25 pages long (A4 size) and details every aspect of the breath test procedure including all necessary questions, answers, warnings and requirements. There is a separate document, the MGDDB, for use when a blood or urine specimen is taken. The MGDDC document details any hospital procedure. The MGDDD document details any technical defence, such as a post driving consumption defence, where back calculations of alcohol should be made (and often fail to be completed correctly) by the police.

The printout showing the result of the breath test should be attached to one of the pages within the MGDDA document. The printout will usually be signed by the completing officer and you, the motorist. The MGDDA document will be signed by the officer and any witness. Like the situation with an intoxilyser printout, the police and CPS believe that the MGDDA document can be used in evidence, as an exhibit. In every case I have dealt with the MGDDA (which includes the printout) is referred to within the Advance Disclosure (documents handed over at the first court hearing) as an exhibit. See the first entry on the “List of Exhibits” in my client’s case:


In actual fact, the MGDDA document and the breath test printout are not exhibits and cannot be presented in evidence as exhibits. Take a look at the guidance for CPS lawyers, taken from the CPS’s own website:


The first paragraph reminds the CPS lawyer to try and get an admission from you. If you admit to something the CPS does not have to prove it! In my view, never admit to anything as far as the MGDDA form goes. You’d be amazed at the mistakes that can be made by the police.

Read the second paragraph. Then read it again. It’s important. Most CPS lawyers don’t seem to realise that the MGDDA document (or the MGDDB/C/D) is inadmissible hearsay. That’s correct - inadmissible hearsay. In other words, it cannot be used in evidence.

But if you agree the MGDDA in an admission, then it can. General rule - don’t agree!

As far as the exhibit issue is concerned, note also the second paragraph. It states: “If the officer who filled out the Form were in the witness box he could not produce the Form in chief as an exhibit”. In other words, the MGDDA document is not an exhibit - whether or not the person completing it is in court!

Even if the officer writes a witness statement referring to the MGDDA document as an exhibit, it still cannot be used as an exhibit! The only way the content of the MGDDA document can be used in written evidence is if the content is incorporated into a witness statement. In other words, the witness statement from the officer should contain all the information on the MGDDA document.

If you have been charged with drink driving, check your MGDDA form and witness statement. I bet that the statement from the officer (even if you have one!) does not contain the information from the MGDDA document.

A quick word of warning. Use a solicitor that knows what they are doing. You do not want to rush off to the CPS and point out its mistakes or ask for a properly completed witness statement prior to the trial date. Remember, they have to prove the case against you. If they have not got the evidence, they have not got a conviction.


I recently represented a different client on a drink-driving charge. I explained to the CPS solicitor at trial that she could not use the MGDDA or printout in evidence. She did not believe me and thought I was joking. She had intended to simply hand over the documents to the Magistrates to read. She insisted they were exhibits and could therefore be exhibited into evidence. After showing her the legal guidance on the CPS website the penny finally dropped. “Oh” she said, “I can’t believe I’ve be using these forms as exhibits for 5 years and no one has ever told me I can’t”. Amazing, but true.

If you have been charged with drink driving and do not remember a MGDDA form being completed with you, the police may have breached the procedure. There are some 20-30 questions that you should have been asked before the police go on to warn you that you do not have to give a breath specimen at all. The police should inform you of what happens if you fail to give such a specimen (known as the statutory warning). Quite simply, if the police failed to warn you of what happens if you fail to provide a specimen then you should not be convicted, even if you went on to provide a specimen.

Note the actual section from the MGDDA document in my client’s case:

Statutory Warning

Section 7(7) of the Road Traffic Act 1988 states:

(7)A constable must, on requiring any person to provide a specimen in pursuance of this section, warn him that a failure to provide it may render him liable to prosecution.

If my client had accepted that this warning was provided to him, he would, in effect, be helping the police to convict him (because the police would not then have to prove this aspect of the offence). However, my client stated that this warning was not provided and so I raised this as an issue in the case. Once this point was raised as an issue it would then be for the CPS to prove it was given. This is an important strategic step. The CPS would need all relevant police officers to attend court at a trial in order to give evidence and be cross-examined. If the police fail to attend court (you’d be surprised how often police fail to attend court) then the CPS would not be able to prove the statutory warning was given.

From a strategic point of view, I would also usually request access to the CCTV taken from the breath test room. If the police fail to keep the CCTV (and often they do) then it may be possible to have the case thrown out of court for what is known as an abuse of process. Even if the CCTV is provided it may show that the breath test procedure was not completed correctly.

Not only did the CPS have to prove that my client was over the limit, it had to prove that my client was driving the car whilst over the limit. This is why the police always prefer it if they stop a vehicle whilst the driver is still in the driver’s seat - it is easier to prove who was driving and that any alcohol in the body must have been consumed before driving.

Of course, in this case my client was arrested some 15 minutes after he was alleged to have been driving. The police did not see my client drive the car, but they did have a witness who apparently saw my client exit the car and run away. Whether or not my client was drunk at the time he was stopped did not, by itself, create an offence. It was necessary for the police to prove he was also the driver.

The police took a detailed statement from the witness who described the driver. Most people would be able to guess what the police should have done next; hold an identification parade. This is much simpler to arrange since most ID parades are completed by video. What should happen is the defendant is photographed looking forward and to each side. He then chooses several other video images of people who look similar. All images are put in a computer ‘line up’ and the witness then views the photographs to see if the defendant can be identified.

The police are well aware of the need for any identification evidence to be collected properly.

Consider the following case of R v Forbes 2000:

ID Parade

Code D, of the police Codes of Practice, which all police should know backwards, states:


Circumstances in which an identification procedure must be held

3.12 Whenever:

(i) a witness has identified a suspect or purported to have identified them prior to any identification procedure set out in paragraphs 3.5 to 3.10 having been held; or

(ii) there is a witness available, who expresses an ability to identify the suspect, or where there is a reasonable chance of the witness being able to do so, and they have not been given an opportunity to identify the suspect in any of the procedures set out in paragraphs 3.5 to 3.10,

and the suspect disputes being the person the witness claims to have seen, an identification procedure shall be held unless it is not practicable or it would serve no useful purpose in proving or disproving whether the suspect was involved in committing the offence. For example, when it is not disputed that the suspect is already well known to the witness who claims to have seen them commit the crime.


You do not have to be a chief inspector of police to understand that an ID parade was not only required, it would also have greatly assisted the police and the prosecution if the witness identified my client.

So, have a guess what the police failed to do. Yes, that’s correct. No ID parade.

Without eye witness evidence, the only way the police could prove my client was the driver was by DNA forensic evidence (see below).

In a case such as this, I would expect the police to seize and forensically examine the clothing from the alleged driver as well as the air bag. A mobile telephone may also contain important data. Let’s consider this in more detail. 

If my client had been the driver then his clothes would contain powder from the air bag explosion. It would be simple to test his jeans, shirt or jacket for such powder. The police did seize his clothes so I expected the police to check for air bag residue. 

The air bag would also be expected to contain DNA from my client such as saliva, blood or skin, assuming he was the diver. The air bag would have been likely to have made contact with his face, usually causing bruises, scratches or even cuts to the skin. The police did take photographs of my client - which did show bruises and a cut.

The police also seized my client’s mobile phone. It would be expected that anyone who had just been involved in a car crash and then ran away would be likely to call someone for help or even try to arrange an alibi. By analysing telephone records the police would be able to see if any call had been made around the time of the crash and, importantly, who received the call. The police would then be able to interview that recipient of the call.

It should also be remembered that forensic evidence can also be used by the defence. For example, if I sent my client’s clothes to be forensically analysed and found no air bag residue, I would then have good evidence that he was not the driver (unless he changed his clothes prior to arrest).

It is also very important to obtain and properly check any forensic report from the police or CPS. These reports will contain scientific and medical language and are difficult to understand to the untrained eye. You may be surprised at the mistakes that can be uncovered (providing, of course, that your solicitor knows what they are doing).


The Schedule of Unused Material is an important document. It should be provided to you within 28 days of a plea of not guilty being entered at court. However, in almost every case I handle the CPS fails to disclose this document in time. This by itself can cause problems for the CPS as a failure to provide evidence within time may result in the case being thrown out, or to place pressure upon the CPS to drop the case.

In my client’s case, the Schedule of Unused Material was served very late. The police listed the jumper, jacket and phone. This indicated that the police did not want to use these items as part of the prosecution case. Why?

From my point of view, it would indicate one of the following:

  • The items were never even tested / analysed.
  • The items were tested / analysed but failed to show anything of benefit to the CPS.

You will also note the code “CND”. This means “Clearly Non Disclosable”. In other words, the CPS did not want to disclose these items to the defence. Why seize my client’s own property and then refuse to return it to him or even allow the defence to see it?

A swab test had been taken from my client following arrest so it would be possible for test for DNA from my client on the airbag. As part out my investigatory work, I discovered that the police had sent away the airbag for forensic testing. This meant that the result of the test must be made available - either as used evidence (and therefore disclosable to me) or unused (and should therefore be listed on the Schedule of Unused Material).

The Schedule of Unused Material did not mention the forensic report so I knew the CPS would want to use the report as part of its case. However, as we got closer to the trial date I realised the CPS had a major problem. If the CPS fails to disclose evidence in time, it is often stopped from using that evidence at the trial.

Due to Government funding shortages, redundancies within the CPS, low morale, staff shortages and poor administration, the CPS often only gets round to sending disclosure to the defence a coupe of days before a trial. Yes, you have read that correctly - a couple of days before a trial. Although the CPS usually has several weeks or months to make disclosure of evidence (as it must do in accordance withy the Criminal Procedure Rules and other legislation), it routinely fails to comply with the law!

“Late disclosure does not worry me. I often use this to win cases.”

Marcus A Johnstone

This case had gone on for several months. The CPS had failed to provide disclosure of evidence within the required timeframe. You will not from the above that the Schedule of Unused Material was also served late. As far as the expert report is concerned, have a guess when the CPS chose to disclose it to the defence… It was only disclosed on the day of the trial!

In fact, prior to arriving at court I had not even been informed that an expert report had been obtained.

The CPS solicitor at court looked very smug when I was handed the report. I was informed by the CPS that, in the CPS’s opinion, it confirmed beyond any shadow of doubt that my client was the driver of the car and, therefore, he should now change his plea to guilty to all charges.

Contrary to the CPS solicitor’s view, my own belief was that we had now dramatically increased our chances of winning the case! Serving a report so late meant that I could apply to exclude the report entirely. The expert had not attended court personally so there was next to no chance of the report being read in court unless I agreed. Note, even if the expert had attended court I would still have been able to exclude the evidence and stop the expert giving evidence, because of late disclosure.

Of course, prior to making any decisions I did take time to read the report and discuss it with my client. What I found in the report was difficult to believe.

Below is a summary of its content.

The CPS instructed its own expert scientist to forensically examine the air bag from the car steering wheel. The CPS’s aim was to find saliva or blood from my client on the airbag. This would be strong evidence that my client was the driver of the car at the time of the accident.

When I received a copy of the expert report / witness statement I was informed by the CPS that, in the CPS’s opinion, it confirmed beyond any shadow of doubt that my client was the driver of the car and, therefore, he should now change his plea to guilty. However, when I carefully considered the report, I actually wondered if the CPS had read it themselves. Let me point out some of the sections that, in my view, did not particularly help the CPS.

The opening paragraph stated:


If this was an abbreviated statement, where was the full statement? It had not been disclosed to the defence. Any expert report that “comprises a limited summary of specific findings” is cause for concern, particularly when we were then informed that the report “does not necessarily cover all items received and / or examinations that have been conducted”.

Anyone reading this would, I’m sure, be asking the same questions. Has the expert chosen to report only those findings favourable to the CPS? Why produce only a “limited summary”? What is the difference between a “summary” and a “limited summary”? Why not examine all items received? Why not report on all items examined?

Considering this was just the first paragraph of a report consisting of several pages, you can imagine my delight at settling down to read the remainder! If this was an abbreviated statement, where was the full statement? It had not been disclosed to the defence. Any expert report that “comprises a limited summary of specific findings” is cause for concern, particularly when we were then informed that the report “does not necessarily cover all items received and / or examinations that have been conducted”. Anyone reading this would, I’m sure, be asking the same questions. Has the expert chosen to report only those findings favourable to the CPS? Why produce only a “limited summary”? What is the difference between a “summary” and a “limited summary”? Why not examine all items received? Why not report on all items examined?

Considering this was just the first paragraph of a report consisting of several pages, you can imagine my delight at settling down to read the remainder!​


The result of any forensic examination was of paramount importance. The expert examined both blood and saliva. The conclusion from the expert was bad news for my client. It stated:


The conclusion of the report was that the DNA found on the airbag was from my client. However, when I considered the main body of the report in detail I became more concerned as to the accuracy and reliability of the expert’s conclusion.

Consider the following wording taken from the report:

DNA profile

”A low level mixed DNA” does not sound too convincing, particularly when the report confirmed the DNA came from “at least three individuals”. Even if my client’s DNA was on the airbag, the prosecution evidence is weakened if the airbag also contained DNA from two other people.

This particular report did not worry me. Even if the report was used in evidence, I felt the court would not agree with the conclusion of the expert. However, I would never take this risk. Much safer to get our own expert to provide our own report and to expand upon the mistakes in the prosecution’s report.

However, due to the late disclosure of the report I did not even have to worry about this. My intention was to simply use the late disclosure, and inaccuracies in the report, to exclude it.

When I read the expert report I seemed to recall an entry on the Schedule of Unused Material. When I cross-referenced it with the Schedule of Unused Material I was pleasantly surprised. See the entry below:


Hang on a minute! No blood found? No fingerprints? Surely if my client had been the driver then his fingerprints would be in the car. If no blood was found in the car, how did the expert conclude that blood was found on the airbag?

After my conference with my client I had a further meeting with the CPS solicitor. She thought that I was about to inform her that we would be changing our plea to guilty. She was surprised when I informed her that she should now drop all charges and, if she did not, I would seek to exclude all her forensic evidence (I briefly explained why). She would then end up with little evidence to prove the identity of the driver - no forensics, no identification parade, no driver!

Two minutes later and all charged were dropped. The CPS solicitor even printed off a letter confirming the case was dropped (see below). We were awarded costs from Central Funds. The letter I later received from the CPS (see below) didn’t quite acknowledge the mistakes made by the police and the CPS but informed us that the case had been dropped because there was not enough evidence!

Case dropped

Needless to say, my client was extremely happy.

The CPS did not like losing this case. Unfortunately the CPS sometimes (most times!) conducts its cases with blinkers on - CPS lawyers believe they have the right person and try to bully people into pleading guilty. The CPS hate it when they have to prove a case based on evidence! This is why I always make them prove every aspect of the case.

As I often say to clients: what have you got to lose? I have dealt with hundreds, if not thousands, of motoring cases over the years. Once a case is dropped by the CPS, it’s over. Finished. However, in this case I received a little surprise.

Worried about cost?

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