Before we start, we should per haps emphasise that there is no way that you could rely on a simple breath tester such as this to determine if you’re fit to drive (or operate machinery, etc).

While it will give you an indication that you are at or over “oh-five”, it could just as easily be reading slightly under when the boys in blue say you’re slightly over.

So be warned – this is not a legal instrument and makes no pretence to be one. Then again, what do you expect for less than $30? (The “real” units cost many hundreds, even thousands of dollars!)

Also, you may not realise that when you’re asked to provide a roadside breath test, even those testers are only supplying a relative reading. If this reading is “over the limit” you will be detained for testing on one of the larger, very accurately calibrated machines. Only at this stage do the Police obtain a blood alcohol level reading which will stand up in court.

Even then, you usually have the right to demand a blood test to determine the actual blood alcohol content (or BAC) because that’s what you are actually charged with.

There is a very close correlation between the alcohol in your bloodstream and the alcohol in your breath but there are reasons why it could be different.

(A quick tip: it’s often higher in the bloodstream than on the breath, so if you’re determined to demand your “rights” you could end up in even deeper doggie doo-dah!).