When Tanis Lambert fatally struck a four-year-old girl in northwest Calgary, it was a "horrible accident" that "could happen to any one of us," said her lawyer after the charge of careless driving was withdrawn mid-trial.

Lambert, 39, was driving a pickup truck when she struck Avi Toulon on May 6, 2016. Toulon, her parents and five siblings were walking back to their home in the Bowness neighbourhood after an outing.

On Thursday, prosecutor Rosalind Greenwood withdrew the charge after witnesses told conflicting stories on Wednesday.

"The Crown has an obligation to continually assess its case," said Greenwood. "The Crown has concluded there is no longer a reasonable likelihood of conviction."

Provincial court Judge Josh Hawkes broke from tradition and commented on the decision to drop the charge.

"In my opinion, this represents an entirely appropriate exercise of prosecutorial discretion," said Hawkes, who thanked Greenwood for "executing this office in such exemplary fashion."

On the day her daughter was killed, Sam Toulon, her husband and their six children were on their way home from a walk to the river at about 8:15 p.m.

As the family made its way through the Bowness intersection, the eldest children were in the lead, and Toulon was bringing up the rear while holding her baby.

She testified the Ford-F150 approached without slowing down, striking and running over Avi in front of her five other children.

But a witness who lived nearby testified that Lambert did stop, even though there was no stop sign and proceeded slowly.

'This was a horrible accident'

That's the same story Lambert told police, said her lawyer, Alain Hepner.

Lambert said in her statement that the child darted out into the street.

"This was a horrible accident, that's what it was; a tragic accident that will affect two separate families…," Hepner said.

"She's distraught," Hepner said of his client. "It could happen to any one of us."

'Very disappointed' parents are suing Lambert

But Toulon and her husband still believe Lambert was negligent.

The couple made a statement through their civil lawyer after the charge was dropped.

"They're very disappointed and very emotional today in this result," said Stephen Nelson.

"We look forward to the full story coming out eventually."

The Toulons are suing Lambert.

Nelson said that with a lower burden of proof in civil matters, he has "no doubt that ultimately we'll be successful in that action."