AlexL
You say that judging aircrew fitness has nothing to do with airport security, but that assumes that they have judged. There is nothing to say that is the case. They smell alcohol, they call Police, who have the equiptment to make a judement as to whether a person has a BAC above a prescribed limit. At no point in that chain, has anyone 'judged' fitness to act as crew.
Reporting people to Police is a common occurance in the UK, and probably in most other countries. Sometimes it is done with malicious intent, mostly however, not. To try to deter those who believe they are being public spirited would be to everyones disadvantage ultimatly.
avrodamo
In the case of people arrested under this act, there is an agreement between ACPO and the CAA that blood will be taken rather than the evidencial second breath test, a delay in results is of course the disadvanage in this agreement. I always found the screening device to be accurate with those I arrested for drink drive, occationaly, someone blew one or 2 points under the limit on the evidience test, but that would be accounted for by time difference between tests and the BAC going down. The same applies to when the Evidiencial screening test machine was not available and blood was taken as an alternative, if the result came back under it was by a margin that would be expected in the time between original test and the doctor arriving at the Station to take a blood sample.