Ontario's highest court has dismissed the appeal of the 2015 impaired driving causing death conviction of 53-year-old Christy Natsis, a dentist from Pembroke, Ont.

In May 2015, after a 55-day trial that stretched over three years, Ontario Court Justice Neil Kozloff found Natsis guilty of impaired driving causing death and dangerous driving causing death, as well as breaching bail conditions when she bought two bottles of vodka about eight months after the crash.

Kozloff ruled that Natsis was drunk when the SUV she was driving crossed the centre line on Highway 17 near Arnprior, Ont., and crashed head-on into a pickup truck driven by Bryan Casey on March 31, 2011.

Casey, who was 50 at the time, later died of his injuries. He left behind his wife, LeeEllen Carroll, and their three children.

Bryan Casey (far left) left behind his wife, LeeEllen Carroll (far right) and their three children. (Submitted photo)

LeeEllen Carroll, Casey's widow, said it was good to finally have the case behind them.

"Seven years ago we lost Bryan to a drunk driver. That is half the length of our youngest child's life," she said. "We have weathered the storm for seven years now. It's time to let out children be children."

Carroll, along with Casey's father, sat through most of the trial, and said the facts of the case never changed.

"Nothing about that night has changed, and we are relieved to see justice being done."

LeeEllen Carroll, Casey's widow, delivered an emotional statement on behalf of her three children after Ontario's top court dismissed Natsis's final attempt to appeal the 2015 conviction. 1:30

In November 2015 Kozloff sentenced Natsis to five years in prison, plus an additional 40 days for breaching the bail conditions.

She served the 40-day sentence, then was released on bail under strict conditions after filing an appeal.

She and her new legal team — Marie Henein and Matthew Gourlay — sought an acquittal or a new trial, arguing that Kozloff made the questionable legal decision to allow the testimony of a biased expert witness — OPP collisions investigator Const. Shawn Kelly — who gave technically flawed evidence.

Crash evidence allowable

Kozloff did exclude some of Kelly's testimony because of concerns of bias, but decided testimony from his calculations and measurements from the collision scene would be allowable. It was that evidence which led to the conclusion that Natsis's vehicle had crossed the centre line before striking Casey's truck.

In the decision written by Justice Gladys Pardu, the Appeal Court found it could see no reason to interfere with Kozloff's conclusions about the admissibility of the evidence.

"Kelly's observations and measurements, and the photographs taken at the accident scene, were admissible as factual observations whether or not his opinion evidence about the conclusions he drew from those observations was admitted," Pardu wrote.

Natsis's lawyers also argued the trial judge should have excluded the expert evidence because the Crown failed to preserve and disclose a draft report prepared by Kelly and submitted to a fellow officer for review.

The report contained a number of errors, including a misstatement about which lane Natsis's vehicle had been in at the time of the collision.

While failing to disclose the document violated Natsis's Charter rights, the appeal court determined that failure did not impair the ability of defence lawyers to argue their case.

Police told CBC News that if Natsis's appeal was dismissed she would have to surrender to the OPP in Pembroke and would be taken into custody.