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The crash on Highway 17 between two SUVs left one man dead. (Supplied photo)

An automotive engineer is expected to be sworn in today as an expert witness at the trial of a Pembroke dentist accused of impaired driving causing death.

Jim Engle with the Ford Motor Company was brought in from Dearborn, Mich., by prosecutors to interpret the data from the power control module of Dr. Christy Natsis's Ford Expedition.

Natsis is charged with impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit in the March 2011 crash on Highway 17 that killed 50-year-old Bryan Casey of Ottawa.

The power control module acts as a type of black box recorder and Engle's testimony could have shed light on how fast the vehicle was travelling immediately before and at the moment of impact, for example.

Ontario Supreme Court Justice Neil Kozloff stopped his testimony on Tuesday, though, and refused to allow him to interpret the data unless he can be sworn in as an expert witness.

Engle is now expected to begin his testimony Wednesday.

Multiple legal challenges

The Natsis trial, which resumed in March after a three-month break, has seen a number of legal challenges already.

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Dr. Christy Natsis is charged with impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit. (CBC)

Defence lawyer Michael Edelson has argued breath samples taken on the night of the crash should not be considered as evidence because the officer who arrested her did not have reasonable or probable grounds to do so.

Edelson also told the court Natsis's Charter Right to fair counsel was denied when the arresting officer terminated her phone call with a lawyer.

Kozloff has yet to rule on the admissability of Natsis's breath samples or on whether her Charter rights were violated.