In Great Britain a legal blood alcohol limit of 80 mg per 100 mL has operated since 1967. Since the introduction of evidential breath testing with a legal limit of 35 mg per 100 mL, the law has enabled those with breath alcohol levels below 40 mg to escape prosecution and those with levels of 40 to 50 mg to opt for a blood or urine sample. The system means that marginal subjects are not prosecuted due to a variety of factors including time delays and analytical tolerances. This paper draws on analytical results and breath/blood interconversions to show how the operation of the law works to the benefit of the drink-driver due to time delays in sampling. It demonstrates that in countries in which the blood option countries in which the blood option applies it means that the real drink-drive limit is about 20 mg above the legal limit. (A)
Abstract