In the UK, basic Plod has a device for the 'roadside' test. It is not accurate enough to read down to 0.20 eg at the aircraft
At the station for a proper test, the machine is also not accurate enough for a reading as low as 0.20 eg at the police station
Eventually a blood sample will be required which takes 6 weeks to analysis.
Some 15 months ago I was randomly tested by 3 officers, CID, Special Branch and Plod in the crewroom after a call from a member of the public who had to be kept anonymous for legal reasons. Obviously I came up as zero on the roadside test. How unfair is that?
The kit I own is more accurate than the roadside kit the Police have, but theirs could ground someone for 6 weeks waiting for results that prove one innocent.
^ Mud sticks!