A B.C. driver has been found guilty of failing her breathalyzer test, despite her claim that alcohol fumes from a burp affected her reading.

Geraldine Louis Guichon was arrested in Sept. 2007 after being stopped at a road block near Anahim Lake. RCMP Const. Spoor said he smelled alcohol coming from her vehicle and brought her to the local detachment to provide two breath samples.

Both results were over the legal limit, and Guichon was charged with impaired driving and blowing over .08.

In a ruling posted last week, provincial court Judge Elizabeth Bayliff found her guilty of the latter charge, saying there was no evidence to suggest Guichon "did actually burp, belch or vomit during either observation period."

The defence argued the arresting officer had been filling out forms while administering the breathalyzer test, and may not have noticed her burping – which can regurgitate alcohol into the mouth and cause a falsely high reading.

During questioning, Spoor admitted that "at certain points in the interview I had looked down" and that he "wasn't staring in her eyes the entire time."

However, the officer was, in his words, almost "within arm's reach" of the defendant. He testified that he was relying on his sense of hearing and smell to detect whether Guichon was burping during the test.

The judge concluded there was no evidence of a "silent and odourless regurgitation which produced mouth alcohol sufficient to falsely elevate one or both of the breath samples."

She also found the fact that both test results were within 20 mg of each other suggested the readings were reliably accurate.

Expert witness Audrey Jakus, an alcohol analyst, testified that the breathalyzer machine used is set up to abort when samples are altered by mouth alcohol, but said it doesn't work when the subject's blood alcohol concentration is low.

Jakus said the lack of "direct, face-to-face" observation during the test meant Spoor had not conducted a proper observation.

The judge concluded that Spoor had not followed guidelines while administering the test, but said it did not account for the results.

She found Guichon guilty of blowing over .08, but not of impaired driving. She wrote that Guichon "operated her vehicle properly" at the road block and was "coherent and reasonable in her manner throughout."

"For these reasons I conclude there is insufficient evidence that Ms. Guichon's ability to operate a motor vehicle was impaired."