In 2021 33,742 people were convicted of drink driving, and the offence is very much on the rise with cases of it trebling over 5 years (between 2017 and the end of 2021).

In 2021 33,742 people were convicted of drink drive, and the offence is very much on the rise with cases of it trebling over 5 years (between 2017 and the end of 2021).

It is legal to have a drink on a night out, and everyone’s tolerance is different, for some people 1 glass would put them over the limit but for others it would have little effect. But how do you calculate your alcohol level – is there a hard and fast rule?

This is where a BAC (Blood Alcohol Content) calculation can help us give you realistic legal advice. We often instruct forensic scientists to do a BAC calculation which can calculate how long alcohol stays in your system and this takes into account factors such as age, height, weight, food and drink. But how does this work in practice ?

Let’s consider a “spiked drinks” example:

Jade was out for a meal with her best friend Sasha, they were having a cocktail and Jade left her glass with Sasha at around 8pm while she took a quick phone call. When she returned, they finished their drinks and had a curry and Jade drove them home at about 10pm.

After she dropped Sasha off, Jade was stopped by the police because her brake light was out. The officer noticed that Jade was slurring her words and asked for a breath sample. Jade blew a 49 on the breathalyser, exceeding the legal limit of 35, and she was therefore arrested and charged with drink drive.

Sasha called Jade the next morning and told her that she spiked her drink with vodka as a joke. Jade then called us for advice on what she could do.

Jade was technically guilty. She was driving with alcohol in her system over the legal limit, but this was not the end of her case.

We listed Jade’s case for a special reasons hearing, this is where we ask the Court to not impose the mandatory driving ban or reduce it owing to special reasons in a case.

By obtaining Jade’s height, weight and what she had eaten that day our expert was able to provide us a calculation on what Jade’s reading would have been had she not had any extra vodka in her cocktail. The expert calculated she would not have been over the limit had Sasha not spiked her drink.

The magistrates found in Jade’s favour finding that she would not have known her drink had been spiked and that her case amounted to special reasons. As a result she was not disqualified from driving.

Details in this case study have been changed to protect the privacy of our client.