There are two reasons to agree to undergo a breath test:
1. You have had little to drink and expect to be borderline or close to the legal limit
Your Breath Alcohol level routinely tests somewhat lower than your Blood Alcohol level. This is essentially because it lakes longer for alcohol to be processed through the body than it does for it to disperse through the breath. Should you have consumed one of the foaming oesophageal plugs such as Gaviscon tablets you can usually expect the breath level to be significantly lower than the blood level.
2. You've had a lot to drink (you're hammered!)
I repeat, your Breath Alcohol level routinely tests somewhat lower than your Blood Alcohol level. If you blow over 1000 without a subsequent blood test or your blood comes out at over 200 mg per 100ml of blood, you are now eligible for HUGELY INCREASED PENALTIES under s.65 of the Land Transport Act 1998 if you have another Driving with Excess Breath/Blood Alcohol offence within 5 years of this offence. This 5 year timeframe applies to both the future and the past 5 years.
So if you adopt the techniques referred to in scenario 1 and manage to produce a breath test result close to but below 1000 you may well be best to stick with it as exposing you to the lesser of two evils.
Of course if you have three offences in five years then you will still attract the penalty increase.
Call me and I will arrange treatment for your obvious alcoholism.
This could be the difference between a Jail sentence or a Community based sentence.