Motions To Exclude Or Limit Evidence Of Retrograde Extrapolation

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Motions To Exclude Or Limit Evidence Of
Retrograde Extrapolation
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Extrapolation back from the BAC at the time of
testing to the BAC at the time of driving is an
endeavor fraught with the danger of
inappropriately bamboozling the jury into
thinking that such an extrapolation can be
anything close to accurate. The information which
is usually available to the expert doing the
extrapolation is woefully inadequate to make even
an educated guess about a range of possible
BACs.
GUESSING BACKWARDS
The generally accepted rate of burn-off is about
one beer per hour, based on the average man.
However, the average man, like the average
family with 2.4 children, doesnt exist the
only rates which have relevance are the rates of
the person on trial. Absorption and elimination
rates are affected by a myriad of factors.
Using an oversimplified model, assume that there
are 20 variable which contribute to the rate of
absorption and that each of these variables has
only 2 values. The mathematical formula for this
model is 2n where n20.
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Factors 1. Weight 2. Gender 3. Physical
Condition 4. Metabolic Rate 5. Time of Day 6.
When Something Was Eaten 7. What Was Eaten 8. How
Much Was Eaten 9. Time Drinking Started 10. What
Was Consumed 11. How Much Was Consumed 12.
Drinking Pattern 13. Altitude 14. Point of
Womans Menstrual Cycle 15. Emotional State 16.
Whether Defendant Is An Alcoholic 17. Inherited
or developed tolerances 18. Whether Medication
Was Taken 19. What Medication Was Take 20. When
Medication was Taken
We can extrapolate in regards to which way each
known factor, in isolation, will affect
absorption and burn-off, but prediction becomes
more complicated each time another factor is
added to the equation. Very quickly, accurate
extrapolation becomes impossible.
If you assume there are only 5 values per
variable (51822), the total number of possible
combination is 3,814,697,265,629.
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Mata v State of Texas (2001) 13 S.W.3rd 1 (2001)
Evidence of Retrograde Extrapolation is
inadmissible unless shown to be relevant and
reliable. Judges are gatekeepers to weed out
JUNK SCIENCE.
Scientific community is divided over validity of
retrograde extrapolation. (Kelly/Frye
Standard) In order for it to have any relevance
or reliability, expert must have evidence of at
least the length of time of drinking, the time of
last drink and the persons weight. Since there
are so many variables (At least 20) The more
factors known to the expert, the more likely that
the application of this theory will be reliable.