Defences to a Drug Driving Charge


Before anything else your lawyer must check out whether or not the police carried out their procedures correctly, when taking you blood sample. There is clear legal case law supporting the proposition that, if the police did not follow procedures correctly, then that is the end of their case: no ifs, no buts. We are not talking here about a mistake in the spelling of your name or your date of birth; but major failings which meant that you were not treated fairly, in accordance with your legal rights, during the evidential blood taking procedure. Unfortunately, unless you instruct a lawyer who knows this area of the law like the back of his or her hand, then any major police mistake may not be spotted.   To attempt to avoid such mistakes the police introduced various forms intended to guide the officer while he/she carries out the evidential blood taking procedure. The forms are intended to make the procedure watertight; defence lawyer proof might be a better description.

These forms are called (a) the MG DD/A, (b) the MG DD/B, (c) the MG DD/E &(d) the MG DD/F.

The letters “MG” stands for “manual of guidance”; the letters “DD” “drink or drug driving”. They have evolved over the years, changing to incorporate legal case law: that is to say as a consequence of a successful legal challenges by defence legal teams, or changes in the legal statutes by Parliament.


(a) The MG DD/A form “Drink and Drugs” Is the basic police document used for any investigation into a possible drink and/or drug driving offence. This is one of the forms which the officer carrying out the evidential procedure at the police station is likely to have with him when requiring that you provide a sample of blood, where he suspects also that you may be over the drink driving limit. It is a complicated document and a brief reading of its 19 pages, may lead you to the view that a stressed-out police officer carrying out the statutory procedure at 4.40 in the morning could be forgiven if he or she made a mistake. His or her mistake, however, could be your “loophole” defence to the charge.

(b) The MG DD/B form “Drink/Drugs Procedure General (Police Station Only)” This is the form which the officer will rely upon when taking blood from you at the police station. Remember that it is only blood which can be analysed if the police are going to be able to later charge you with drug driving. The saliva test you perhaps gave at the roadside when you were stopped, is not an evidential sample: it merely gives the officer cause to suspect that certain drugs are in your system, and cannot by itself form the basis for a successful prosecution. The form is uniquely complicated and, some would say, no longer fit for purpose; forcing the officer to jump through various hoops regarding your consent to giving a sample in the first place; the statutory warning; the taking of that sample by a suitably qualified medical practitioner; storage and continuity of transportation, of that blood sample, to the forensic science laboratory, etc., The scope for mistakes to be made, at any point during the overall procedure, is blindingly obvious. Any such substantive mistake equals your later letter of discontinuance from the Crown Prosecution Service, or finding of innocence by the court.

(c) The MG DD/E form “Drug Drive Laboratory Submissions” This form, the “drug specimen information form”, will be sent with your blood specimen to the forensic laboratory. The form is designed to permit the investigating officer to give as much information as possible to the forensic scientist. It allows not only for information to be given concerning the drug suspected, but also the results of any breath alcohol test upon you. The officer will note on the form your physical condition, for instance if you had vomited, were drousy, hyperactive, etc., He will also note any other background information and information which you might provide; should you choose to provide it. Therefore, anything you say (for instance that you had smoked cannabis earlier in the evening), which might help the police prove their case against you, will find itself on to this form. Whether or not anything you say which might help your case, will be noted on the form on this form is perhaps another matter. Numerous clients facing these allegations are shocked when they receive copies of these forms months later to see that their “of the cuff” remarks were noted and form an important part of the prosecution case against them. It is important for you to remember that this form, together with the blood sample, will form the basis of any case against you. If the officer should foul up when completing this form then that may have dire consequences for any successful prosecution, by interfering with the ability of the laboratory to carry out essential secondary confidence checks, upon the results of their initial analysis of your blood.

(d) The MG DD/F form “Roadside Impairment Testing” This “preliminary impairment test” form [a blank copy of which you can access here] has the potential to become a vital part of the police case against you. A “ preliminary impairment test” will normally happen at the roadside though the officer who stops you has a discretion as to venue. The procedure involves a number of tests and is governed by a 2017 Department of Transport 12 page Code of Practice. The Code states that the officer “shall have regard” to it (the “Code”) when carrying out the test. How many officers have read the “Code” is not known. What is known is that any officer who carries out the procedure, upon a suspect, must be suitably qualified and authorised by his/her chief constable; and have received the appropriate training: not every officer is so authorised. Moreover, the testing is not straightforward and the temptation for a harassed and overstretched officer, late on a Saturday night, to simply give you a saliva test and be done with it, is likely to be intense. However, if such testing is not carried out then this may have dire consequences if the officer should later wish to charge you with the old section 4 offence of driving whilst unfit, if the police discover later that they cannot charge you with new section 5A offence; perhaps because the blood sample analysis procedure was compromised in some way, or for some other reason. The reason for this is because, without having persuaded you to carry out a “preliminary impairment test” the police may have little, if any, evidence that you were impaired; impairment, of course, is what they must prove in any driving whilst unfit prosecution, the old section 4 offence. Even a cursory glance at the description of a “ preliminary impairment test” in the drop-down below, will demonstrate why an officer, even if suitably qualified, might be inclined to rely upon a straightforward saliva test rather than the cumbersome and time consuming test. 

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