Further to the interesting question asked by
Daysleeper:
Having looked at the Act again, I could find nothing to support the FODCOM suggestion that the specimen requested at the police station will in practice "usually be a specimen of blood", or the ATSIN suggestion that "in practice this will usually be "a sample of the suspected offender’s blood or urine."
As I've explained already, the Act expressly adopts the road traffic legislation and the usual practice in road traffic cases is to request a further specimen of breath measured by a calibrated evidential breath-test machine. (The law only requires the police to request or offer the blood or urine procedure in limited circumstances.)
I've discussed the issue with the Deputy Head of Flight Ops at the CAA who was very helpful and, between us, we arrived at what
may be the explanation - it relates to the Police Protocol I mentioned in my earlier response:
The FODCOM reflects agreements reached between many bodies, including the CAA, Home Office and the Police. A 'Police Protocol' has been created to guide police officers applying and enforcing the new legislation. It
may be that, in aviation cases, the police have agreed to request a specimen of blood rather than the usual second specimen of breath.
I emphasise this is no more than a possible explanation. I don't have access to the internal Police Protocol ( yet
) but the CAA will find out and come back to me. I hope to be able to post a definitive answer by the end of the week.
It seems credible because, under the present procedure, if your reading on the evidential machine at the police station is only just over the prescribed limit, the police must give you the opportunity to provide a sample of blood or urine for analysis.** That suggests an acceptance that the machine cannot give as precise a reading as is obtained from blood/urine analysis. Given that the aviation limits are lower (except for engineers), it may be that the police have agreed miss out the machine stage and go straight to the blood procedure.
However, this is speculation on my part. I have nothing to support it.
** Subject to any medical considerations, the choice of blood or urine is made by the police, although the suspect can express a preference. They almost invariably opt for blood because that is taken by a doctor and it avoids an officer undertaking the unpleasant and often messy task of taking a urine sample from someone who's drunk.)
Tudor Owen