Difficulties with testing for new drug driving law

A further difficulty in testing for drugs in relation to the new drug driving laws has been raised by ROAR Forensics in a report.

Currently the police take around 5ml to test for alcohol, experts say that this will not be sufficient for drug testing  “in order to cover the proposed drugs and provide a quantitative result (notably in poly drug misusers, which is common in the UK) there will be a requirement to obtain more blood than current practice. Approximately 10ml of blood could be required compared to the current 5ml sample.”

This is not as easy as it sounds, it can be difficult to obtain that amount of blood

“To ensure that there is sufficient sample to permit the analytical requirement there would have to be a minimum volume, notably as at present it is not uncommon to receive far less than 5ml.”

But it doesn’t end there, the defendant has to be provided with an equal quantity for him to have his sample analysed.

“There is then the issue of ensuring that there is a similar volume available for the defendants sample (assuming that, as now, a divided aliquot is provided to the defendant)”

Having managed to get the correct amount of blood will the defence be able to get it tested? ROAR believe that currently there are very few laboratories that offer this service for the defence. In drink driving this may not be that significant unless the reading was very close to the limit however with all of the difficulties with actually testing for drugs this could well be a valid argument if the defence have not been given the opportunity to have their sample tested.

For further advice on drug driving call us on 01623 600645

Drug Driving back calculations

A not unfamiliar scenario with drink driving is where there is a delay between driving and giving a breath or blood test. This can occur for a number of reasons such as when someone is arrested sometime after driving or are unable to give a breath sample so a blood sample is required and it takes a while for a health care professional to take blood.

By the time the blood or breath sample is taken the driver may be under the limit. The police may believe that the driver would have been over the limit at the important time, that is to say when he was driving. They are able, with the assistance of an expert, do a back calculation to establish what the reading would have been at the time of driving.

It’s likely that the same sort of scenarios will arise with drug driving and the police will want to establish what the reading was at the time of driving.


As simple as that, any delay that allows the driver to go below the limit means that there will be no way to establish that he or she would have been over the limit at the time of driving. 

Whilst the back calculation is relatively easy for alcohol for drugs, because of the many variable in what the body does to drugs, back‐calculation is much more difficult and was considered to be impracticable by the Panel set up by the government to review this.

If you have been charged with a drug driving offence call us for expert and honest advice on 01623 600645

How accurate will blood tests for drugs be under new Drug Driving law?

The new drug driving law relies on blood test to establish not just whether there are drugs in the driver’s blood but also the type and quantity. Clearly accuracy is going to be of paramount importance here. The results will decide whether someone is guilty or not. Whether they are disqualified or not.

The scientific community has a lot of experience in the testing of blood for alcohol and it tends to be fairly accurate, it is rare that two tests on the same blood differ by much.

Without the experience for testing for quantities of drugs will the drug tests be as accurate. A number of commentators suggest that there is genuine cause for concern.

LGC laboratory pointed out that the analysis for drugs in blood is not as standardised as it is for alcohol due to the many factors involved. The quality of alcohol measurements is significantly better as there are Certified Reference Materials (CRMs) available to demonstrate accuracy and to give lower measurement uncertainty. The Government recognises these issues and is currently working with toxicology providers to understand the extent of any analytical variations and develop guidance to ensure any potential impacts are minimised.

Whether these issues can be ironed out before injustices occur remain to be seen.

To speak to a Drug Drive Solicitor call 01623 600645