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437. Blood test
A blood test can be used to measure the concentration of alcohol in a person’s blood. A healthcare professional takes a blood sample, which is then analysed in a laboratory to determine the blood alcohol concentration (BAC). In traffic enforcement, blood testing may be used when breath testing is impossible or unsuitable, after an accident or as a counter-analysis to a breath result. The circumstances in which a blood test can be required and the legal alcohol limits vary between countries.
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What is an alcohol blood test?
An alcohol blood test measures the concentration of alcohol in a blood sample and provides a blood alcohol concentration (BAC).
How is a blood test different from a breath analysis?
A blood test measures alcohol directly in the blood, while a breath analysis measures alcohol in exhaled breath. Both can be used to determine whether a legal alcohol limit has been exceeded.
Who takes the blood sample?
A blood sample used for legal testing is normally taken by an authorised healthcare professional and analysed according to an approved procedure.
When can a blood test be used after an alcohol control?
Depending on local law, a blood test may be used when breath testing cannot be performed, after certain accidents or as a counter-analysis of a breath result.
How is a blood alcohol result expressed?
Blood alcohol concentration is commonly expressed as grams of alcohol per litre of blood, parts per thousand (‰) or a percentage, depending on the country.
Can refusing a required blood test lead to penalties?
Yes. In countries where a blood sample can lawfully be required, refusing without a legally accepted reason may itself be an offence.

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