UK drink driving laws and the legal limit

Police can use different types of alcohol tests depending on the situation. A roadside breath test is the most common. Drivers may be asked to blow into a handheld device after a traffic offence, collision, or suspected drink driving incident. The device estimates the amount of alcohol in a person's breath within seconds.

If the roadside test suggests someone is over the limit, they're usually taken to a police station for a more accurate evidential breath test. This uses a larger machine designed to provide a legally admissible reading.

In some cases, blood or urine samples may be used instead. This can happen if a breath test can't be completed, if the equipment is unavailable, or if officers believe drugs may also be involved. Samples are normally taken at a police station or medical facility and analysed to confirm alcohol levels.

Scotland lowered its limit in 2014 to improve road safety, creating a split in UK rules. There's ongoing discussion about whether England and Wales may also adopt a lower limit in future.

Why is there no safe number of drinks you can have before driving?

There's no safe number because alcohol affects every driver differently. The same amount of alcohol can impact different people in very different ways. Even the same person can be affected differently from one day or week to the next, making it impossible to predict a consistent response.

Some factors that can affect alcohol levels include:

• Age: Your metabolism and liver efficiency typically slow down over time.
• Sex: Differences in body composition and enzymes can affect how quickly alcohol is processed.
• Metabolism: People who process alcohol faster will usually see effects wear off sooner.
• Stress levels: This can alter how the body responds to alcohol and its effects on judgement.
• Food intake: Eating before or while drinking can slow the absorption of alcohol into the bloodstream.

Because of this, you can't accurately calculate whether you're over the legal limit based on drinks or units alone. Even small amounts of alcohol can slow reaction times and affect judgement. This means you could still be unsafe to drive, even if you're under the legal limit. The safest choice is not to drink any alcohol before driving.

What are the penalties for drink driving?

Drink-driving laws in the UK are strict, and penalties are designed to deter offending. If you're caught over the limit, you could face the following:

• Up to 6 months in prison
• An unlimited fine
• A ban from driving for at least 1 year (3 years if convicted twice in 10 years)

More serious offences, such as causing death by careless driving while under the influence, can result in life imprisonment and a minimum 5-year driving ban. Failing to provide a breath, blood or urine sample carries similar penalties.

How long does drink driving affect car insurance?

A drink driving conviction has long-lasting effects on your car insurance. A DR10 conviction must be declared to insurers for at least five years. This significantly increases premiums because insurers classify convicted drivers as high risk.

Many mainstream insurers may decline cover altogether, meaning drivers often need specialist insurance providers. Once a driving ban ends, it's important to compare policies carefully to help reduce the cost of your car insurance.

How long does alcohol stay in your system for driving?

Alcohol leaves the body at a slow and steady rate, but this varies between individuals. On average, the body processes around 1 unit per hour, but this isn't exact. For context, a pint of beer can contain around 2 to 3 units, a large glass of wine around 3 units, and a single spirit measure around 1 unit.

This means alcohol can remain in your system the next morning after a night of drinking. Sleeping doesn't speed up the process. Only time reduces alcohol levels. A heavy drinking session can easily leave someone over the limit well into the following day.

When were drink-driving laws introduced in the UK?

Drink driving laws have developed over time. Early legislation in the 1920s made it an offence to be “drunk in charge” of a vehicle. The modern framework began with the Road Safety Act 1967, which introduced legal alcohol limits and roadside breath testing. In 2014, Scotland introduced a lower limit, creating the current difference in UK law.