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San Diego DUI Prosecution Expert’s assumed “BAC” – Make an ASS out of U and ME

In San Diego DUI trials, the Prosecution ultimately marches in their paid laboratory person to "assume" what the San Diego DUI driver’s BAC allegedly is.

San Diego DUI defense attorneys readily wait their turn.

In each case, a San Diego DUI prosecutor first asks the "state’s expert" to answer the following hypothetical question(s):

Q. How many drinks would be in the San Diego driver’s system at the time of the test, in order to reach a (insert BAC number) as was obtained on the San Diego DUI breath test machine?

or

Q. How many drinks would a (insert San Diego driver’s weight and sex) person have to consume between (insert start drinking time) and (insert end drinking time) in order to obtain a reading of (insert BAC # Prosecution wishes to contend) on the (insert San Diego DUI breath test machine – the Intoxilyzer or Intoximeter)?

The San Diego DUI prosecutor is introducing evidence with numerous assumptions.

It would be a Denial of Due Process and the Right to Confrontation to deny a San Diego DUI criminal defense attorney’s turn to have an opportunity to then materially cross-examine the witness, as follows:

Mr./Ms. Prosecution lab person, please identify every assumption that you needed to make in order to make the calculation that gave you the specified number of drinks as the answer to the San Diego DUI Prosecutor’s hypothetical question:

Did you assume an average size drink?

Did you assume an average human absorption amount?

Did you assume an average human absorption time?

Did you assume an average human burn-off rate?

Did your answer assume a true BAC or blood alcohol level?

Is it true there is established science correlating levels of impairment to blood alcohol levels?

Is it true there is no such similar science correlating levels of impairment to breath alcohol levels (especially on San Diego DUI breath machines that do not have the ability to distinguish mouth alcohol from deep lung alcohol)?

Is it true you had to therefore assume an average conversion rate between the amount of alcohol contained in venous blood and the corresponding amount of alcohol that should theoretically be contained in a deep lung sample of breath?

So, the assumption for average drink size has a range?

So, the assumption for average absorption rate has a range?

So, the assumption for average burn off rate has a range?

So, the assumption for average absorption time has a range?

If your assumption for the drink size were to change value, your answer would change.

If your assumption for average absorption rate were to change value, your answer would change.

If your assumption for average burn off rate were to change value, your answer would change.

If your assumption for average absorption time were to change value, your answer would change.

If your assumption as to the conversion rate were to change value, that would also change your answer.

Of all the assumptions you made, the most highly-changing or volatile assumption is the conversion rate.

The conversion rate changes between the amount of alcohol contained in venous blood and the corresponding amount of alcohol that is contained in a deep lung sample of breath.

This means any San Diego DUI breath machine BAC reading must have a possible range of actual blood alcohol level results.

A San Diego DUI defense lawyer can therefore show why it is not a good idea to "ASSUME" when trying to determine one’s true BAC.

Assuming through averages does not necessarily amount to proof of true BAC beyond a reasonable doubt.

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By: Rick Mueller

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