You might use a personal Breathalyzer machine to work out when you are safe to drive without being over the limit. Yet, putting your faith in it could get you charged with driving under the influence (DUI)>
When it comes to Breathalyzers, the only ones the police or a court will be interested in are the official police ones. If you blow negative on your machine, then test positive on a police machine, you will get a DUI.
The only thing that counts is your BAC when the police test you
Breath devices measure your blood alcohol content (BAC), which can change from one moment to the next. When you consume alcohol, it takes time to make its way into your bloodstream. So if you blow into your personal Breathalyzer when leaving the party, it may read less than if you blow into the police a half an hour after.
Breathalyzer machine models also vary in their accuracy, and even two identical machines could read differently if one has been calibrated recently and one has not. It’s important to remember that a device that’s been tossed in your bag or purse or fixed to your keychain has probably bounced around a lot, and that can affect the readings it gives.
Is there any point at all in buying a personal Breathalyzer?
Do not rely on a store-bought Breathalyzer to tell you that you are safe to drive. However, if you already own one, you could use it to indicate when you are definitely not safe to drive. That is to say, if you blow positive, do not get behind the wheel of a car. If you blow negative, you still need to decide based on other factors, such as how many drinks you had and how long ago you had them.
If charged with a DUI, your Breathalyzer will not save you. However, it may give you a clue that something was wrong with the police machine if the two machines read very differently. Even police Breathalyzers can be inaccurate, and you may be able to challenge them.