#calibrationcurve

Maybe the Instrument Is No Longer Linear Enough to Be An "8000C"

May 22, 2018
5 min

Maybe the Instrument Is No Longer Linear Enough to Be An "8000C"

Purpose: To explore the analytical variability of the 8000C as determined by the Alcohol Test Committee during evaluation of the 8000C prior to type approval. To compare the analytical variability of the individual 8000C used in the subject tests for the client with the analytical variability of the type or class 8000C determined by the Alcohol Test Committee. To suggest that the instrument in the matter before the Court may no longer be a member of that class or type because

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BAC Analysis in a Lab Without Bracketing Controls is at Best Qualitative not Quantitative

Stephen Biss

Apr 27, 2018
4 min

BAC Analysis in a Lab Without Bracketing Controls is at Best Qualitative not Quantitative

We have a serious problems in the Canadian criminal justice system. One of them is the failure of Parliament and the Courts to recognize the differences between a qualitative measurement (a screening device result like a rapid home use COVID test kit or a roadside breath ASD, PBT, or ADSE tester result) and a quantitative measurement that results in criminal law sanctions. The Criminal Code and our case law, to some extent recognize the differences between an approved instrum

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Change at One Point but Not at Another Point that is Equivalent

Stephen Biss

Apr 13, 2018
5 min

Change at One Point but Not at Another Point that is Equivalent

This is a sample excerpt from a cross-examination of a Crown expert using data from periodic inspection of an approved instrument. The multiple-point control test data from an annual periodic inspection in Ontario or from a re-calibration as in Vallentgoed can be very useful to the defence in cross-examing a breath tech or a Crown expert to identify drift in accuracy and precision over time. Purpose: To suggest that there is empirical evidence in the matter before the Court o

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Why Does the ATC Say Single Point Control Tests are Good Enough?

Stephen Biss

Mar 25, 2018
6 min

Why Does the ATC Say Single Point Control Tests are Good Enough?

Purpose: To explore the differences between a measurement instrument that has a linear relationship between the thing measured and the result v. a measuring instrument that has a calibration curve. To search for an admission that the calibration curve can shift up or down, left or right, or rotate around a point over time. To cross-examine the CFS expert on the lack of empirical study supporting the ATC/CFS hypothesis that a single point control test can always detect drift.

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Stephen Biss

Mar 23, 2018
3 min

Response Drifts Over Time

In an article relied upon by the SCC in St. Onge, Brian Hodgson stated: Defence lawyers need to educate themselves about the meanings of "drift" and "over time". What is it that actually "drifts"? What happens "over time". Are these concepts important to clarify during any cross-examination of a Crown expert? Can the reality of drift over time be satisfied by single point control tests? Is more required to maintain reliability over time? The ATC and CFS regularly opine that a

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8000C Auto-Calibration Sequence - How to Run the Auto-Calibration Sequence

Stephen Biss

Mar 1, 2018
6 min

8000C Auto-Calibration Sequence - How to Run the Auto-Calibration Sequence

Purpose of this cross-examination: To educate the Court about the calibration sequence run on the approved instrument at the factory. To obtain an admission from the Crown expert that without the proper auto-calibration AND creation of a unique calibration curve, the instrument is not reliable. Every individual instrument has a unique calibration curve. Every individual re-calibration at the factory or at the factory-authorized Canadian service centre produces a unique calibr

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Traceability of Measurement Result on an Approved Instrument

Stephen Biss

Feb 14, 2018
4 min

Traceability of Measurement Result on an Approved Instrument

Purpose: To obtain an admission from the CFS scientist that the traceability of a measurement result on an approved instrument or a truck weigh scale is through the calibration of the instrument at the factory or a proper recent re-calibration by the manufacturer or factory authorized service centre. At the time of calibration a calibration curve is created to establish a relationship between the electrical signal coming off the detector in the AI or the weigh scale and the d

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Instrumental Deviations from Beer-Lambert Law

Stephen Biss

Jan 11, 2018
10 min

Instrumental Deviations from Beer-Lambert Law

This blog entry explores the use of a university textbook during cross-examination of a CFS scientist on "Instrumental Deviations from Beer-Lambert Law". The purposes of this cross-examination included: To explore the reasons why measurement instruments in the field may deviate from the linearity alleged by the Beer-Lambert law. To introduce a university textbook dealing with inter alia: External Calibration Creating a Calibration Curve Limits to Beer's law No longer linear w

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