Reliability: 64 in 2011 Ambient Threshold Changes, Elevated Zero, Purge Fail

Updated: Sep 13


This is the same Intoxilyzer® 64 with upgraded keyboard and (software) serial number depicted in the blog "Ambient Conditions Change Baseline 0 on an IR Breath instrument - Disappearing Alcohol". These experiments were run in 2011. In this experiment the operator has attached a 50 mg/100mls target alcohol standard to the breath tube to simulate a breath room with 50 mg/100 mls ambient alcohol in the air.

Please note that the instrument in this video will not, on a cold start, sound an alarm and shut down with either 10 or 20 mg/100mls ambient alcohol in the air. This experiment shows that the instrument does not sound an alarm or shut down with 50 mg/100mls of ethyl alcohol placed into the breath tube on start-up:

Rather, the instrument adjusts itself by raising the ambient threshold 50 mg/100mls:

The point is that this instrument does not flag ambient ethyl alcohol beyond a fixed threshold in the way that scientists used to think when the 5000C was first approved in Canada. Rather the instrument adjusts its zero value in accordance with ambient conditions. These are IR machines that float zero.


If you take a close look at the CFS 8000C Training Aid of 2013 you wiil see an acknowledgement of the floating system blank test threshold (page 70 of 238). Note that in their example, the system blank test threshold has been varied from 10 mg/100mls to 19 mg/100mls. The same phenomenon may repeat to increase the threshold to 28 mg/100mls or 37 mgs/100 mls if ambient alcohol (or an interferent) are increasing in the room. Depending on the stability of that ambient alcohol (or interferent) in the room there may or may not be a purge fail message.



Excerpt from CFS 8000C Training Aid
CFS 8000C Training Aid 2013 p. 70 of 238 excerpt. Note that they may be correct in saying that subject tests won't be overestimated, BUT the reliability of the control tests required by 320.31(1)(a) are compromised.

It is the operator who is ultimately responsible for controlling adverse ambient conditions. The automatic machine ambient fail systems only flag rapid changes in ambient conditions from one air blank to the next, exceeding a threshold change of value of 10 or 19 mg/100mls.

It is therefore not safe to assume that cal check or breath test sequences with no "ambient fail" messages have not been compromised by ambient alcohol or an ambient interferent.

In assessing the impact of this phenomenon please be careful not to fall into the error of equating "reliability" with "accuracy". Many Crowns and government scientists will say: "A raised threshold will NOT elevate subject breath test results, it will reduce them." The defence should concede that assertion. That's not the point. The issue is St-Onge lack of reliability (and 320.31(1)(a) lack of reliability) through operator error (and maybe instrument malfunction depending on maintenance/calibration of the threshold), not Carter evidence to the contrary contradicting accuracy. Fluctuating ambient conditions compromise cal. check reliability. If the operator doesn't control properly for this phenomenon, then cal. checks are unreliable. If cal. checks are unreliable then the approved instrument is unreliable. Note that the CFS will likely concede that a cal. check below 90 is as unacceptable as a cal check above 110. The issue is reliability. Lack of reliability through operator error, malfunction, (or lack of maintenance), should negate the 258(1)(c) presumption or 320.31(1)(a) conclusive proof.

Quaere: Quite apart from operator error in not controlling ambient conditions, if this instrument has not been maintained/serviced for many years, can we count on the calibration of its system blank test threshold values? Do they drift over time? Shouldn't those ambient flag threshold values be annually inspected against known standards in accordance with manufacturer's specifications?

WARNING: These videos and blog comments are NOT EVIDENCE. The author is not an expert. The author is not a scientist. This blog entry is provided to encourage discussion among defence lawyers.

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