The police still have to prove impairment.

I think.

To be honest, it's not all that clear.

Hi all, I was employed by the MoT as a scientist during some of the time this drug driving legislation was being worked out (I have moved on since then). I did the reading the of research papers, etc, etc.

Anyway, unless something has changed the police will have to prove impairment yeah. So should will go something like

- Cop pulls you over, suspects you are driving under the influence of drugs (mostly likely after giving you an alcohol test which you pass)

- You then have to exit the vehicle and do a road side impairment test, this is kind of like what some US states still use for Alcohol. This means that according to the research it is quite conservative, in that it will more often give a false negative (fail to detect impairment by drugs) and a false positive.

- Assuming you have failed this, you are now considered impaired and will be required to give a blood test. I think also you might be stopped from driving for a bit - 24 hours maybe, like with current fails of alcohol - because well you are impaired.

- The blood test will then be sent away to be analysed and if drugs are found you will be prosecuted, if not, then nothing happens.

At least that is the outline of what would go down, if my memory serves me. Pretty reasonable really, all things considered.

Russell is right though about the ads, I remember discussing it with the advertising folks, a tricky issue for sure in terms of how to say its illegal to take drugs and drive (if you are impaired) when technically speaking the person you are giving the message to has already broken the law by taking the drugs. Fun stuff.

Oh, and yeah the research for the effectivenss of lowering BAC is pretty clear. Plus come on, with our current BAC an average male can drink something like 4 or 5 standard drinks in an hour and still be allowed to drive... yikes (note - its about 2 standard drinks in a hour if the limit was lowered to 0.05)