In England and Wales, it is an offence to drive a motor vehicle when the proportion of alcohol in your system is above the legal limit – s.5 Road Traffic Act 1988.
The drink-driving limit in England and Wales is 35 micrograms per 100 Millilitres of breath, 80 Milligrammes per 100 millilitres of blood or 107 Milligrams per 100 millilitres of urine.
There are various reasons why this law is in place, the most obvious reason being to protect the safety of pedestrians and other road users.
When a person consumes alcohol it can affect their ability to drive safely. This is because the processing of information becomes more difficult which can lead to delayed reaction times and your ability to judge certain situations are impeded. This could ultimately lead to a road traffic accident.