Drink Drive Limits UK: The Law, the Tests, the Consequences

#The two UK limits

In England, Wales and Northern Ireland, the legal limit is 80 milligrammes of alcohol per 100 millilitres of blood, equivalent to 35 micrograms per 100 millilitres of breath. In Scotland the limit was lowered in 2014 to 50 milligrammes of alcohol per 100 millilitres of blood, equivalent to 22 micrograms per 100 millilitres of breath. Both limits also have a urine equivalent used in lab testing.

#Why a unit calculator does not work in practice

Body weight, food, hydration, gender and time since the last drink all change blood alcohol level. A 65 kg woman will be over the limit on a single pint of strong lager in many cases. A 90 kg man might be on the same pint. Online calculators can only ever give a rough idea. The only safe rule is: if you are driving, do not drink. If you have been drinking, you cannot trust your own judgement on the limit.

#How police test you

A police officer can require a roadside breath test if they reasonably suspect you have been drinking, if you have committed a moving offence, or if you are involved in any collision. The roadside device gives a pass, fail or refuse to test result. A fail leads to arrest and a more accurate test at the police station with a calibrated breath analyser.

If the breath analyser cannot be used (medical reasons, intoxication, or technical fault), the police can require a blood or urine sample. The test result is then compared against the legal limit. Refusing to provide a specimen without reasonable medical excuse is itself an offence and carries the same penalty as a positive test.

#The morning after problem

Alcohol leaves the body at roughly one unit per hour, but the rate varies and the count starts only after the last drink finishes processing. Two large glasses of wine at 10 pm can leave you over the limit at 8 am the next morning. If in doubt, take public transport or sleep for longer. Personal breathalysers from £30 give a rough indication but should never be trusted as a clear-to-drive test on a marginal reading.

#The penalty for a positive test

The minimum penalty for drink driving in the UK is a 12 month disqualification, a fine, and the DR10 code on your licence. Courts add up to six months in prison for serious cases or repeat offences. Driving 50 mg above the limit can mean the maximum fine and a custodial sentence even on a first offence.

A DR10 stays on the licence record for 11 years. It must be declared on every insurance application during that period. Most mainstream insurers will not quote at all in the first two to five years after the offence. Specialist firms such as Sky Insurance or AAIB will quote but at premiums roughly three to four times higher than a clean driver.

#Causing death or serious injury while drink driving

If a fatal or seriously injuring collision is caused while drink driving, the offence escalates. Causing death by careless driving while over the limit carries up to 14 years in prison and a minimum five year ban. Recent changes also raised the maximum sentence for causing death by dangerous driving (which can include drink driving) to life imprisonment in the most serious cases.

#The drink drive rehabilitation course

When the court imposes a ban of 12 months or more for drink driving, you may be offered a place on a Drink Drive Rehabilitation Course. The course costs around £180 to £250 and runs for several sessions across two to three weeks. Completing it shortens the ban by up to 25%, sometimes more. Most defendants accept it because the saving in time off the road is significant.

#High risk offenders

Some convictions trigger high risk offender status. This includes very high readings (over 200% of the limit), refusal to provide a specimen, two convictions in 10 years, or being unfit through drink. High risk offenders must apply for a fresh licence and pass a DVLA medical including a blood test before being allowed to drive again.

#How drink driving affects work

A DR10 conviction can end careers in driving for a living, including taxi, HGV, courier and emergency services. Some employers terminate on the day of conviction. Even office jobs that require occasional driving may not be possible during the ban. Plan around the impact on income before deciding whether to drive after a drink. The cost of a taxi or hotel is small next to a year off the road.

#Practical rules new drivers should follow

Three rules cover almost every case. Decide before going out whether you are driving home. If you are, drink soft drinks only. If you are not, leave the car and book transport in advance. Never drive the morning after a heavy night without a clear gap of at least 12 hours from the last drink. For wider context, see licence points and disqualification and young driver insurance UK. The first month after passing guide also covers common first year mistakes new drivers make on this exact topic.