Many people assume that providing a sample over the legal limit means automatic conviction. This is simply not true. Our experienced drink and drive solicitors regularly identify and successfully argue numerous technical and procedural defences that result in charges being dropped or acquittals at trial.
1. Challenging Breath Testing Procedures
Breath testing devices must follow strict operational procedures under Section 7 of the Road Traffic Act 1988 and PACE Code C. Even minor procedural breaches can render results inadmissible. Our drink and drive solicitors examine:
Improper Warning Given
Police must warn you under Section 7(7) that failure to provide a specimen may render you liable to prosecution. This warning must be clear, unambiguous, and given in terms you understand. If the warning was absent, unclear, or given after you attempted to provide, the entire procedure may be invalidated.
Insufficient Observation Period
Police should observe you for at least 20 minutes before evidential testing to ensure you don’t consume alcohol, regurgitate, vomit, or use mouth sprays. If this observation period was not properly maintained, breath test results may be unreliable due to mouth alcohol contamination.
Device Not Properly Calibrated
Evidential breath testing devices require regular calibration and maintenance according to strict schedules. Calibration records must be available for inspection. If calibration was overdue or records unavailable, our drink and drive solicitors challenge the device’s accuracy and reliability.
Failure to Provide Two Valid Samples
The procedure requires two breath samples, and the lower reading is used. If the device failed to obtain two valid samples, or if there were significant discrepancies between readings (typically more than 15%), this undermines reliability. Our drink and drive solicitors use these discrepancies to challenge the evidence.
Device Malfunction
Breath testing devices can malfunction due to software errors, sensor degradation, environmental factors, or radio frequency interference. Maintenance logs and error messages can reveal device problems that affected your reading.
2. Medical Conditions Affecting Test Results
Certain medical conditions can artificially elevate alcohol readings. Our drink and drive solicitors work with medical experts to demonstrate these conditions:
Gastroesophageal Reflux Disease (GERD)
GERD causes stomach contents to reflux into the mouth, introducing “mouth alcohol” that doesn’t reflect true blood alcohol levels. This mouth alcohol can significantly inflate breath readings. Medical evidence from your GP or gastroenterologist can support this defence.
Diabetes and Ketoacidosis
Diabetic ketoacidosis produces acetone on the breath. Some breathalysers cannot distinguish between acetone and ethanol, potentially producing false positive results. Medical records documenting your diabetes, HbA1c levels, and recent ketone episodes support this defence.
Respiratory Conditions
Asthma, COPD, and other lung conditions affect breathing patterns and breath volume, potentially influencing breath test accuracy. Inhaler use immediately before testing can also contaminate results.
Dental Work and Dentures
Dental work, crowns, bridges, and dentures can trap alcohol in the mouth, artificially elevating breath readings through mouth alcohol contamination rather than reflecting true blood alcohol levels.
3. Rising Blood Alcohol Defence
Your blood alcohol level continues rising for 30-90 minutes after consuming your last drink. This phenomenon, known as “post-drinking absorption,” means you may have been under the limit while driving but over the limit when tested 30-60 minutes later at the police station.
This “rising blood alcohol” defence succeeds when:
- You consumed alcohol shortly before driving
- Significant time passed between stopping driving and evidential testing
- Back-calculations performed by forensic toxicology experts demonstrate you were likely under the limit while actually driving
Our drink and drive solicitors instruct expert toxicologists who perform these complex calculations. By presenting scientific evidence showing your blood alcohol was rising during the critical period, we can secure acquittals even when the evidential reading exceeded the limit.
4. Hip Flask Defence
The “hip flask defence” applies when you consumed alcohol AFTER driving but BEFORE providing the evidential specimen. Section 15(3) of the Road Traffic Offenders Act 1988 specifically provides for this defence.
Common scenarios include:
- You were involved in an accident, and before police arrived, you consumed alcohol to calm your nerves or treat shock
- You arrived home and had a drink, then police knocked on your door
- You consumed alcohol while waiting for police at the roadside
To establish this defence, you must prove on the balance of probabilities that you consumed alcohol after driving. Evidence includes witness testimony, receipts, CCTV footage, and expert back-calculations showing the alcohol consumed after driving accounts for exceeding the limit.
Our drink and drive solicitors know precisely how to present this complex defence effectively.
5. Laced or Spiked Drinks Defence
If someone spiked your drinks without your knowledge, you may have a complete defence. You must prove:
- You consumed alcohol unknowingly
- Someone else added alcohol to your drinks
- You had no reason to suspect drinks were spiked
- You were not reckless in consuming the drink
Toxicology evidence, witness testimony, and expert analysis support this defence. Our drink and drive solicitors gather this evidence and present it compellingly to the court.
6. No Evidence of Driving
The prosecution must prove beyond reasonable doubt that you were driving or attempting to drive. If police didn’t witness you driving, our drink and drive solicitors challenge this fundamental element:
Circumstantial Evidence Insufficient
Being found in or near your vehicle doesn’t automatically prove driving. If there are no witnesses, no CCTV, and you made no admissions, the prosecution cannot prove you drove.
Alternative Explanations
Perhaps someone else drove the vehicle to its location. Maybe you were a passenger. Possibly you were simply sitting in the parked vehicle. Without proof of driving, the prosecution case fails completely.
Identification Issues
Even if witnesses claim they saw someone driving, can they positively identify you as that person? Our drink and drive solicitors challenge witness identification evidence rigorously.
7. Special Reasons Not to Disqualify
Even if convicted, “special reasons” arguments can persuade the court not to impose the mandatory driving ban or to significantly reduce its length. Special reasons are:
- Circumstances peculiar to the offence itself (not the offender)
- Not amounting to a defence
- Directly connected with the commission of the offence
- A matter the court ought to take into consideration
Examples of Special Reasons:
- Laced drinks where you consumed alcohol unknowingly because drinks were spiked
- Shortness of distance where you drove only a very short distance (a few meters) in an emergency
- No likelihood of driving where you had no intention to drive on a public road
- Medical emergency requiring immediate driving to obtain urgent medical assistance
However, special reasons are difficult to establish and require expert legal presentation. Our drink and drive solicitors know precisely how to present special reasons arguments that courts will accept.
8. Procedural Errors Under PACE
The Police and Criminal Evidence Act 1984 (PACE) and Code C govern police procedures for detention, treatment, and questioning. Breaches can render evidence inadmissible. Our drink and drive solicitors examine:
- Whether you were properly cautioned
- Whether you were given adequate information about your rights
- Whether you were denied access to legal advice when requested
- Whether custody procedures were properly followed
- Whether detention was lawful and necessary
- Whether interviews were conducted properly
Even a single procedural error can be fatal to the prosecution’s case.
9. Contamination and Mouth Alcohol
Breath tests can be contaminated by “mouth alcohol” that doesn’t reflect true blood alcohol levels. Sources include:
- Mouthwash and breath sprays containing alcohol
- Recent consumption (alcohol still in mouth, not yet absorbed)
- Regurgitation or belching (bringing stomach alcohol into mouth)
- Dental work trapping alcohol residue
- Medications containing alcohol
If mouth alcohol contaminated your sample, the reading doesn’t accurately reflect your actual blood alcohol level. Our drink and drive solicitors present evidence of contamination to challenge prosecution reliability.
10. Challenging Sample Analysis
For blood and urine samples, numerous issues can undermine prosecution evidence:
- Improper sample collection procedures
- Chain of custody issues
- Contamination during storage or transport
- Laboratory errors in analysis
- Sample not analyzed within time limits
- Results not properly certified
Our drink and drive solicitors instruct forensic experts to review laboratory procedures and identify errors that cast doubt on sample reliability.