San Diego DUI Defenses - Breathalyser Tests

The level of alcohol in your bloodstream can be accurately measured by testing the alcohol on a person’s breath. Advantages of using the breathalyzer to measure someone’s Blood/Breath Alcohol Content (BAC) instead of administering a blood test are that it is quick, easy, cheap and painless whilst still being accurate. Blood tests on the other hand require a more highly trained operator and more controlled testing, processing and storage of the resulting blood sample, which translates into much higher administrative costs.

However, there are many situations which can seriously affect the accuracy of a breathalyzer test and a qualified San Diego DUI attorney will be very familiar with all of them. For instance, breathalyser machines assume the body temperature of the person who is blowing into the machine to be 34 degress centigrade but for each degree over that temperature the test result will come back 7% higher than it should. A woman on her menstrual cycle or a person with a fever can be 2 degrees above that average temperature, and when you take into account the manufacturers published variance of 5% it is within reason that a breathalyser test result can easily give readings that are 20% higher than they should be in certain circumstances. Just because your BAC was measured at over 0.08% by a breathalyser machine doesn’t mean that you will automatically be found guilty of DUI in San Diego.

Situations that can affect the accuracy of a breathalyzer test are:

Burping or belching in the 15 minutes leading up to the test
Vomiting or belching just before the test without having the chance to rinse your mouth out.
Recent exposure to volatile fumes such as gasoline or paint fumes, causing chemical interference which can falsely elevate the BAC test result.
Your actions and behavior clearly contradict the high reading, with independent witnesses testifying that you appeared sober.
You have a dental condition, such as dentures or root pockets that can trap and hold alcohol in the mouth, giving a falsely elevated BAC reading.
Respiratory problems such as bronchitis or asthma can affect the test result.
There was something in your mouth that caused interference with the BAC test result, such as tobacco, strong mints or chewing gum.
Breathalyzer operator fails to follow standard procedure for administering the test.
Your breathing was irregular and you were crying when you blew into the breathalyzer resulting in an artificially high water vapor content which interfered with the test result.
Legislatively imposed breath to blood ratio of 2100:1 which the breathalyzer results are based upon is shown by independent experts to be far
off what your own actual personal breath/blood ratio. You are a diabetic whose body has naturally high levels of isopropyl alcohol after consuming only a small amount of alcohol.
State of California cannot prove that the BAC test results were obtained within the statutorily imposed 3 hour time limit after driving.
Elevated breath temperature can interfere with the test result, possibly caused by menstrual cycle, recent sauna, detention in hot police car in summer or a high fever.
Several tests done to achieve an accurate reading may have large discrepancies, showing problems with the machine. Or if BAC is higher on last test can use that data to to show that BAC would have been below 0.08% at time of driving.
Radio frequency interference from a cell phone can cause the breathalyzer to record an unusually high test result.
If your airbag was deployed then the gas propellant can cause diffusion of light in breathalyzer, leading to inaccurate results. Air bags were invented after the breathalyzer.