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Hip Flask Defence


The Road Traffic Act 1988 contains a number of offences connected with drink or drugs, including the offence of driving or being in charge of a vehicle whilst being above the legal limit for alcohol.

A specimen of breath, blood or urine from a driver suspected of any of these offences will normally be taken by the police for use in the case against him.

The effect of section 15 of the Road Traffic Offenders Act 1988 (the RTOA) is that it will be presumed that the level of alcohol in the specimen was at least the same as the level of alcohol in the suspected driver’s breath, blood or urine at the time of the alleged offence. i.e Whatever your reading then the court reckon that this was the reading when you were driving or in charge of the vehicle.

However if a driver drank after the alleged offence, then the level of alcohol in the specimen will obviously be higher than the level of alcohol at the time of the alleged offence. This is often referred to as the “Hip Flask Defence“. It comes from the reference of an accused to taking a drink from his hip flask to steady his nerves after a road accident. Nowadays Sheriffs are suspect of this defence and it will take a great deal to persuade one that you were so shocked by an accident that you had to have a drink to calm yourself down. The social climate has changed since the hip flask defence first made its way into the courts of Scotland and most Sheriffs would want to hear a VERY GOOD reason for you taking the decision to drink especially where you would know or reasonably expect the police to become involved in the investigation of an road traffic incident.

In cases where the suspected driver drank alcohol after he stopped driving or being in charge of the vehicle but before the specimen was taken, section 15 of the RTOA provides that it is a defence to show that the post-incident drinking caused the specimen to have a reading which was above the legal limit.

What does the ” Hip Flask” defence need to prove?

Usually the crown have to prove your guilt but here we have the situation where we, the defence have to establish your innocence! OK, we do not need to prove it “Beyond a reasonable doubt” but the standard that we require to meet is still a high one.

The defence must show that the post-incident drinking caused the specimen reading to be over the legal limit on a balance of probabilities that is, a greater than 50% likelihood.

The defence case has to be particularly strong to overcome the presumption in section 15 of the RTOA. The driver’s evidence of what he drank must be verified by commissioning a toxicology report from a qualified expert.

We would normally call upon the services of a respected and experienced forensic toxicologist to compile a report based on the facts in your case.

This report will show what the effect of the post-incident drinking had on the specimen reading. The expert will calculate the rate at which the your body processed the alcohol that was consumed. The expert must be provided with accurate information on the following, if a worthwhile report is to be compiled.

  • How much you drank after the incident
  • The alcohol content of what you had to drink
  • The time of the post-incident drinking, and the period over which you drank
  • Height, weight, age and sex of accused

If a driver had nothing to drink before the incident (that is, he only drank afterwards), the defence would have to lead evidence of this fact. If a driver drank before the incident and had a post-incident drink, the defence would have to lead evidence that any pre-incident drinking did not put him over the legal limit. The defence should ask the toxicologist to calculate what the specimen reading would have been on the basis of the driver’s pre-incident drink.

The prosecution may use an expert toxicology report to show that, even if the post-incident drinking is discounted, the driver would still have been over the limit when he was driving or in charge of the vehicle. Remember, section 15 of the RTOA contains a presumption that the level of alcohol in the specimen was at least the same as the level of alcohol in the driver’s breath, blood or urine when he was driving or in charge of the vehicle. It therefore allows for the possibility that the level could have been higher than the level in the specimen.

This is a difficult defence to establish and it requires expertise not just from the toxicologist but from the solicitor conducting the case. A great deal of case law exists in this area and it is a legal minefield for the uninitiated and even for many experienced solicitors.

Graham Walker

Graham Walker

Road Traffic Lawyer at
Road Traffic Lawyer: Graham Walker LLb,DipLP,NP

30 Years practising as a Criminal lawyer in Scotland. Specialising in road traffic law. Whatever the road traffic law problem is we are sure that we can help you. It may be about speed cameras, Speeding fines, penalty points. Call 0800 612 9597.
Graham Walker
Graham Walker
Graham Walker