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Incidence of "Invalid Sample" Screen Messages on the Intoxilyzer 5000C Obtained From Arrested Drinking Drivers in Toronto: Is a 15 to 20 Minute Wait Period Warranted?

NCJ Number
Canadian Society of Forensic Science Journal Volume: 39 Issue: 3 Dated: September 2006 Pages: 101-113
J-P. F.P. Palmentier; J. G. Wigmore; R. M. Langille; J. Patrick
Date Published
September 2006
13 pages
This article reports on a 5-year retrospective study of "INVALID SAMPLE" screen messages obtained on the Intoxilyzer 5000C from drinking drivers arrested in Toronto, Canada.
The study concluded that most of the 196 "INVALID SAMPLE" screen messages produced by 184 drivers tested on the Intoxilyzer 5000C were likely due to variations in the breath exhalation pattern of the subjects; therefore, a mandatory waiting period of 15 to 20 minutes following every occurrence of an "INVALID SAMPLE" screen message is not required. Such a waiting period may be required; however, if a qualified breath technician has reason to suspect that mouth alcohol may be a factor in the error message. Among the subjects tested, single "INVALID SAMPLE" screen messages (n=173) occurred more often than repeat messages (n=11). Eighty-eight of the single messages occurred prior to the first breath test, and 85 occurred prior to the second breath test. The time in police custody before a single message ranged from 27 to 223 minutes and from 59 to 199 minutes for multiple occurrence of the message. This length of time eliminated the possibility that the results were influenced by a mouth alcohol effect. The time between the screen message and the subsequent breath sample retest after single messages ranged from 2 to 61 minutes (mean of 5 minutes), and the time until retesting after multiple messages ranged from 3 to 65 minutes. The duplicate breath test results for all cases (single and multiple messages) were within 0.02 g/210L, and no third breath test was required. For breath tests that were conducted less than 20 minutes after the screen message, no evidence was found of a mouth alcohol effect that resulted in the next breath test being significantly higher due to mouth alcohol. 5 tables, 4 figures, and 31 references


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