Post-Driving Consumption Defence: How It Works & Why It Can Win Your Drink-Driving Case

By MAJ Law on 01 December 2025

If you have been charged with drink driving, you may feel that the case against you is already stacked beyond repair. For many people, the breath reading taken at the police station feels like the end of the road. But in reality, the law is much more complex, and sometimes the reading taken at the station tells only part of the story.

One of the most powerful legal arguments available in drink-driving cases is the post-driving consumption defence. This defence applies where you consumed alcohol after driving but before the police carried out the procedure. When used correctly, it can completely undermine the prosecution’s case.

At M.A.J Law, our specialist drink-driving solicitors have used this defence to successfully challenge hundreds of cases. In this article, we explain how it works in practice and why it may be the key to saving your driving licence.

Understanding the Law: Section 15(2) RTOA 1988

Most drink-driving prosecutions rely on the reading taken at the police station. Under Section 15(2) of the Road Traffic Offenders Act 1988, that reading is treated as your alcohol level at the time of the test, not necessarily your level at the time of driving.

Crucially, this means the prosecution do not need to prove your exact alcohol level when you were behind the wheel.

Instead, the law places a legal burden on you, the defendant, to persuade the court, on the balance of probabilities, that you were not over the limit at the time of driving. This is the foundation of the post-driving consumption defence.

What Is Post-Driving Consumption?

Post-driving consumption simply means that you drank alcohol after returning home, parking the car, or waiting for recovery. This is far more common than people realise, and often completely innocent.

Examples include:

  • Having a drink to relax after a stressful journey

  • Drinking while waiting for a recovery truck

  • Having a drink because you genuinely believe you’re not going anywhere else that night

  • Sharing a drink with a friend after arriving home

The problem? Alcohol takes time to absorb into your bloodstream. You can be fully sober at the wheel but over the limit an hour later when the police test you.

Why Post-Driving Drinking Affects Your Reading

Alcohol does not absorb instantly. The time it takes for alcohol to reach its peak concentration in your bloodstream depends on many factors, including:

  • How much you drank

  • What you drank

  • Your body weight

  • Your food intake

  • Your metabolic rate

If you drank alcohol after driving, and that alcohol was still being absorbed at the time of the police station test, your reading may reflect post-driving alcohol, not your true level when driving.

This is where the defence becomes so powerful.

The Role of Expert Evidence

To establish the defence, scientific evidence is vital. At M.A.J Law, we work with some of the UK’s leading forensic toxicologists.

The expert will analyse:

  • The amount of alcohol you consumed after driving

  • The time you consumed it

  • Your personal physiological factors

  • The timings of the police arrival and breath test

  • The scientific absorption curve

They then carry out a retrograde calculation, which essentially works backwards from the police reading to estimate your alcohol level at the actual time of driving.

In many cases, the expert evidence shows that the motorist was likely below the limit when behind the wheel.

Real Example: Case Dropped After Expert Calculation

We represented a client who drove home after a short trip, then drank two large glasses of wine. A neighbour later called the police. By the time officers arrived, the alcohol had begun to absorb. He blew over the limit at the station.

Our expert analysed the timeline and concluded that he was below the legal limit while driving.

The CPS had no option but to withdraw the case.

Your Burden: The Balance of Probabilities

Because of Section 15(2), the defendant must show that - on a balance of probabilities - they were not over the limit at the time of driving. This doesn’t mean “beyond reasonable doubt”. It means something much lower: simply that your version is more likely than not.

With credible evidence, consistent timing, and expert support, this threshold is often met.

Supporting Evidence We Can Gather

The CPS may attempt to argue that the post-driving drink never happened or that the account is fabricated. That’s why corroborating evidence makes such a difference.

We gather:

  • Witness statements

  • Photographs

  • Till receipts

  • CCTV

  • Phone logs and messages

  • Evidence of alcohol containers or glasses

  • Timeline reconstruction

When paired with reliable expert evidence, the defence becomes extremely difficult for the prosecution to challenge.

Should You Plead Guilty?

Absolutely not - not until the evidence has been properly reviewed.

Many people plead guilty early because they believe the breath reading is final. Others are wrongly advised that they have “no defence”. Once you plead guilty, the court cannot revisit the legal or scientific arguments.

If you drank anything after driving, no matter how small, you should speak to us immediately. The timing may be the difference between conviction and acquittal.

Why Choose M.A.J Law?

Drink-driving defence is all we do. We are one of the largest specialist motoring-defence firms in England and Wales, with one of the highest success rates nationwide.

We win cases because we understand:

  • The law

  • The science

  • The evidential procedure

  • The weaknesses in police investigations

We represent clients across the country and challenge hundreds of drink-driving cases every year, many of which are dropped because of technical arguments like post-driving consumption.

Contact M.A.J Law Today

If you’ve been charged with drink driving and think the post-driving consumption defence might apply to your case, contact us today.

We offer:

  • A free initial assessment

  • Expert forensic analysis

  • Fixed-fee representation

  • National coverage

  • Decade-long experience in defending drink-driving allegations

Call M.A.J Law on 0151 422 8020 or submit an enquiry online.

Your driving licence, career, and reputation are too important to risk. Let us help you build the strongest possible defence.

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