Within Thames Valley an average of 16 people each day are arrested for drink driving. Drink driving is not just an offence that happens around Christmas and New Year, it is happening throughout the year.

What are the limits?

In technical terms the current legal limits are: 35 micrograms of alcohol in 100 millilitres of breath; 80 milligrams of alcohol in 100 millilitres of blood; 107 milligrams of alcohol in 100 millilitres of urine.

Each alcoholic drink is measured in units of 10 milligrams of alcohol. Drinks are allocated a unit measurement depending on their alcoholic content.

Often people can be putting themselves at risk by driving after consuming alcohol the night before and still having it in their system when they get behind the wheel.


On average, it takes about one hour for your body to break down one unit of alcohol. However, this can vary from person to person, depending on:

  • your weight
  • whether you’re male or female
  • your age
  • how quickly or slowly your body turns food into energy (your metabolism)
  • your stress levels
  • how much food you have eaten
  • the type and strength of the alcohol
  • whether you’re taking medication and, if so, what type

It can also take longer if your liver isn’t working normally.

It’s simply far too difficult to tell exactly how much alcohol will take you over the limit. It’s much better and safer to lay off the drink completely if you do have to drive. You can still have a great night out without alcohol – You can even avoid the dreaded hangover the day after!

If you do want to drink you should take into account the alternatives:

Use a taxi – or even better share one!

Use public transport – you’ll even be doing your bit to help the environment!

Designated driver Arrange for someone who is not drinking to drive.

This advert from Think! makes it pretty clear, but there are other consquences so read on:

Think before you drink!

If you are convicted for drink drive offence you will:

  • Lose your licence for a minimum of one year
  • You may go to prison for up to six months
  • You may have to pay a fine of up to £5,000
  • You may lose your job (15 per cent of those convicted do)
  • Have a criminal record
  • Face exceptionally high insurance costs once you get your licence back
  • Have difficulty hiring a car within ten years of your conviction

For more information about the effects of driving under the influence of alcohol please see the DfT’s Think! Website


Driving under the influence of drugs – whether prescribed medication or illegal substances – is just as dangerous (And in some cases more) as driving under the influence of alcohol. It’s also against the law.

Drugs can affect your mind and body in a variety of ways that mean you aren’t able to drive safely. Not only that, the effects can last for hours or even days.

Drug tests

The police can carry out roadside tests of impairment to help them decide whether to arrest you if they think you are unfit to drive through drugs. The penalties are the same as for drink driving. You face a minimum one year driving ban, a fine of up to £5,000, and six months jail time.

How Drugs Affect Your Driving:

  • Slower reaction times
  • Poor concentration
  • Sleepiness/fatigue
  • Confused thinking
  • Distorted perception
  • Over confidence, so you take unnecessary risks
  • Impaired co-ordination
  • Erratic behaviour
  • Nausea
  • Hallucinations
  • Blurred vision/enlarged pupils
  • Aggression
  • Panic attacks and paranoia
  • Tremors
  • Dizziness
  • Cramps