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Causation of Error v. Calculation of Drift in Precision - Evidence Based Assessment of Reliability

February 10, 2018

What is the purpose in Stinchcombe/McNeil disclosure or O'Connor production of maintenance records and historical data?

Crown CFS scientists are right in saying that there is no causal relationship between the historical data and the results of a subsequent subject test.

Crown CFS scientists are incorrect in saying that maintenance records and historical data are irrelevant in assessing the scientific reliability of a measurement result.

Control tests, cal. checks, and simulator temperatures do not change Intoxilyzer results! They do not cause error in Intoxilyzer results! You can operate an Intoxilyzer and get an accurate result with no wet-bath simulator or dry gas attached to the Intoxilyzer (however you would get zero cal checks).

The point is scientific reliability of the measurement result. Lawyers need to understand the meaning of "scientific reliability of the measurement result"

Lawyers and Judges need to understand that many factors determine the correctness AND RELIABILITY of the tests.

The many factors are NOT limited to factors apparent at the time of the subject tests.

If a Crown, Judge, or CFS scientist starts heading in the direction of asking defence to prove malfunction or operator error causation of the results, a conscientious defence lawyer needs to re-direct the Court's direction to impact on "reliability" as contemplated by the SCC in St-Onge citing the Hodgson paper and R. v. Lam in Ontario.

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If you are a Canadian criminal defence lawyer and you wish to learn more about cross-examination on these issues, we suggest that you visit the Members page at www.impaired-driving.com and enroll in the three online courses that are described therein. Once you have completed the three online courses, you can apply to become a full Member at that site, and if you are accepted for membership, you will have access to the much more extensive Members Only Blog at that site, as well as  additional international resources, links, and materials.

If you are a Canadian criminal defence lawyer and you wish to learn more about cross-examination of Drug Recognition Experts we recommend that you attend an online or recorded session at  https://www.impaired-driving.com/dre-tutorial.

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