§ Mr. Wolfsonasked the Secretary of State for the Home Department whether his Department has given any guidance or instruction to forensic science laboratories to deduct a value of 6 mg. from the average analytical value for alcohol in blood or urine in drink drive cases in order that results may be expressed as being "not less than x mg. per 100 ml."; and what is the scientific basis for current practice in this regard.
§ Mr. MayhewForensic science laboratories have been advised to deduct 6 mg. where the mean of the analyses lies between 11 mg. and 100 mg. per 100 ml. and 6 per cent. where the mean is above the latter figure. This deducation is made to safeguard the motorist by allowing for at least three times the coefficient of variation of the analytical method, thus taking account of the known margin for error in any analytical determination.