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Evidential Breath Testing

Volume 81: debated on Tuesday 25 June 1985

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asked the Secretary of State for the Home Department when he will publish the report by the forensic science service on evidential breath testing; what conclusions he has reached on the basis of his consideration of the report; and whether he will make a statement.

The Home Office forensic science report on the monitoring of the Lion intoximeter and Camic breath analyser evidential breath testing machines is being published today, together with a foreword by the independent scrutineer, Sir William Paton, and subsequent correspondence I have had with him. Copies have been placed in the Library.It is clear in the light of this report that both types of instrument and their procedures are fundamentally acceptable in the sense of not placing subjects unjustly in jeopardy. We therefore intend to continue to use them as the principal means of assessing for evidential purposes whether a person's capacity to drive is impaired by alcohol to an extent which justifies criminal proceedings.The report finds that a fault in the acetone detector in the Lion intoximeter leads to under-estimation of the level of alcohol in occasional cases. This fault may result in a motorist who is in fact over the legal limit escaping prosecution, but not to a motorist who is below the limit being prosecuted. The report also finds that in a few cases there were large differences between individual breath sample results within a pair of breath samples. Some of these large differences appeared to be associated with the malfunctioning of the acetone detector. We accept the report's recommendation that: where this difference exceeds a prescribed amount a blood or urine test should be substituted.We will make arrangements for the evidential breath testing instruments in use by the police to be modified to take account of both these findings.The use of these machines enables many more drink-drive offenders to be dealt with quickly and the report makes it clear that the machines deserve public support, in the interests of road safety. Pending the findings of Sir William Paton's study, the blood-urine test has remained an option. The numbers of those who take this option have steadily declined and the latest figure available (March 1985) shows a take up rate of 16 per cent.

I think it right to allow the option to continue for a while longer, but I am not convinced that there is a long-term case for retaining it and I intend to review the position in 12 months time with a view to withdrawing the non-statutory option.