TORONTO - Ontario's highest court has ruled a mother was wrongfully convicted in the death of her infant son, clearing her of the baby-killer label hanging over her head for 13 years due in part to evidence of the now disgraced pathologist Dr. Charles Smith.

Both the defence and Crown called for Sherry Sherret-Robinson's acquittal at a hearing Monday in the Court of Appeal for Ontario due to new expert evidence that "conclusively refutes critical aspects" of Smith's opinion.

"The appellant's conviction was wrong and she was the victim of a miscarriage of justice," the three-judge panel said, returning their ruling after weighing the arguments for about 20 minutes.

Sherret-Robinson's lower lip quivered as the judges told her: "You were wrongfully convicted."

To hear those words, exonerating her of deliberately smothering her four-month-old son Joshua 13 years ago, was a great relief, she said.

"It lifted a huge weight off my shoulders," Sherret-Robinson said outside court.

"To be able to know that it's actually been acknowledged, that I don't have to continue to say, 'I didn't do anything,' it just meant a lot."

Smith concluded the boy, Joshua, died of asphyxia and that his death was suspicious due in part to a skull fracture and neck hemorrhages.

But Dr. Michael Pollanen, Ontario's chief forensic pathologist and other experts found there was no skull fracture and the neck hemorrhages were in fact caused by Smith during the autopsy.

The experts concluded there is no basis in the pathology to support Smith's inference that the baby was deliberately smothered or suffocated, but that it can't be ruled out.

Instead, Pollanen suggested, the autopsy findings and the fact that Joshua had numerous layers of blankets under, around and on top of him, "reasonably support the conclusion that death occurred by an accidental asphyxial means in an unsafe sleeping environment."

A report on pediatric forensic pathology from Justice Stephen Goudge last year found the failings of the "arrogant" Smith, once considered the dean of his profession, and his bosses were at the heart of several miscarriages of justice.

Though Sherret-Robinson had initially pleaded not guilty to infanticide, the Crown and her lawyer drafted an agreed statement of facts that said she smothered Joshua, causing his death, and she was found guilty in a Belleville, Ont., court in 1999.

In an affidavit filed with the Court of Appeal, Sherret-Robinson says she has always wondered if she put too many blankets around Joshua that night and now will have to live with the knowledge that it probably led to his death.

"I will never forget the terror I felt when I reached down to pick him up and discovered that he was blue and his little body was completely stiff," she writes.

After the police arrived, the next thing she remembers is sitting in the emergency room, hugging a picture of Joshua and sobbing.

"Eventually the doctors came and told me he had died, and let me hold him to say goodbye," Sherret-Robinson writes.

"I sang him a lullaby and refused to let go of him. Even to this day I cannot get that image out of my head."

Goudge referred to Sherret-Robinson's case in his report, saying Smith "inappropriately" formed his opinion using matters outside the pathology, such as statements Sherret-Robinson had made one month before the death that she was depressed and was going to smother her baby.