To convict an individual of driving under the influence, the state must prove your blood alcohol content at the time you were driving. Your breath reading an hour or two later is not what proves you guilty of a DUI. Your breath test results at the time you were driving are what are important.

Your breath test results at the time you were driving had a lot to do with the following factors:

  • How much you weigh
  • Your metabolism
  • What you ate
  • How much you ate
  • When you ate
  • What you drank
  • How much you drank
  • When you started drinking
  • When you stopped drinking

In order for the state to prove that you were over the .08% legal limit at the time you were driving, they will have to “extrapolate”, or estimate, what your breath alcohol reading was at the time you were first stopped.


If you are pulled over in the state of California on suspicion of driving under the influence (DUI) of alcohol, the officer will most likely give you the option of choosing between a blood and breath test in order to determine your blood alcohol content (BAC). The exception would be if the officer suspects you of driving under the influence of drugs, in which case a blood test will be administered.

Different individuals hold varying opinions as to which of these tests is the best choice to opt for when asked by an officer. In general, the breath test is regarded as slightly less accurate and more error-prone than the blood test. In many situations, breath tests have been known to render falsely high results. Furthermore, breath samples – unlike blood samples – cannot be kept for future verification.

Yet the accuracy of the blood test could make these results less debatable in court. A defense attorney could have more success arguing the reading of a breath test than that of a blood test. Furthermore, if you suffer from certain respiratory ailments including asthma and emphysema, you could be unable to qualify for a breath test.

CALL Fiumara & Milligan Law, PC TODAY

For over 24 years and thousands of DUI cases, Fiumara & Milligan Law, PC have been defending people charged with DUI. Since chemical testing regulations are often followed incorrectly, we can help determine if we can build a defense using said improper actions for your case.

Please call our office today at (707) 571-8600 in our centrally located Santa Rosa office in Sonoma County or call our office in San Rafael in Marin County at (415) 492-4507 to schedule a free and confidential case evaluation.