Drink drive ยท Drunk in charge

Alcohol technical defence

Blood, breath or urine alcohol calculations for drink drive and drunk in charge cases. We estimate your probable alcohol level at the time of driving, and whether you were likely within the legal limit.

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What we can report on

These are the areas we work on most often, though the list is not exhaustive. If your issue is not shown, get in touch and we will tell you whether the science can help.

Post-driving consumption

Drinking after you stopped driving (the "hip-flask" defence), and whether alcohol taken later accounts for the reading.

Failure to provide

The science behind failing or refusing to provide a specimen, including medical or physical reasons a sample could not be given.

Laced drinks

Unknowingly consuming spiked or laced drinks, and the effect this had on your breath, blood or urine alcohol reading.

Device malfunctions

Questions over the reliability, calibration and correct operation of the breath-testing device used.

Medications & acid reflux

How certain medicines, mouthwashes and conditions such as acid reflux (GORD) can affect a breath alcohol reading.

Procedure & analytical data

Examination of procedural irregularities and detailed review of the analytical data pack behind the result.

The science, explained

How an alcohol calculation works

From your record of what, when and how much you drank, together with your body characteristics and the timeline of events, we estimate the most likely range of alcohol in your blood, breath or urine at the relevant time.

This can show whether you were probably within the prescribed limit while driving, support a post-driving drinking account, or test the strength of the prosecution's evidence. Every calculation is set out in plain English, with workings you can check.

Discuss your case
Typically needed

What helps us report

  • A record of drinks: type, strength, amount & timing
  • The MG DD/A or B forms & procedure records
  • The analytical result & data pack
  • Body weight, height & relevant medical history
  • The timeline of driving, arrest & testing
Don't have everything? Get in touch anyway.

Charges this covers

Driving over the prescribed limit
Section 5, Road Traffic Act 1988
In charge over the prescribed limit
Section 5, Road Traffic Act 1988
Driving whilst unfit through drink or drugs
Section 4, Road Traffic Act 1988
In charge whilst unfit through drink or drugs
Section 4, Road Traffic Act 1988

Alcohol defence FAQs

A back-calculation estimates your blood or breath alcohol level at an earlier point, usually the time of driving, from the reading taken later at the police station. It uses established rates of alcohol elimination and your account of consumption.
In some circumstances conditions such as gastro-oesophageal reflux (GORD), certain medications and mouth alcohol can be relevant to a breath reading. Whether it applies to your case depends on the specific facts, which we assess independently.
Timescales depend on the complexity of the case and the material available. We agree a realistic timeframe with you at the outset and can often accommodate urgent court deadlines, so please ask when you get in touch.
Yes. ATXpert produces court-compliant expert reports and can give oral evidence in person or by video link where required.

Facing a drink driving charge?

Get in touch for free scientific advice or a no-obligation quote. A short conversation will tell you whether an alcohol calculation could help your case.

Get free advice Email contact@atxpert.co.uk