April Halkett was found not guilty in June 2009 of abandoning the baby boy two years earlier in the store in Prince Albert, Sask.
But the Crown disagreed with the verdict and took the case to the Saskatchewan Court of Appeal, which upheld the findings of the trial judge.
Justice Neil Gabrielson had ruled that he believed Halkett's testimony that she didn't know she was pregnant and left the store because she thought the child was dead. He described it as "a case of a scared young woman being confronted with unexpected circumstances."
Dean Sinclair, director of appeals for Saskatchewan Justice, said Thursday it will be the first child abandonment case to be heard by the Supreme Court.
He said the court needs to clarify the intent behind the charge. Do people have to act reasonably in the circumstances or act according to what they honestly believe?
Halkett testified that she thought the baby was dead and that she was abandoning a corpse.
"We're arguing a reasonable parent would have checked to see if the baby was alive or dead," Sinclair said.
Steven Penney, a law professor at the University of Alberta, said the Crown has a tough case to prove.
"It's going to be difficult to convince the Supreme Court to revisit the factual findings," said Penney. "All of the courts so far have accepted that she didn't realize the baby was alive."
Halkett was 20 years old when she walked into the department store's washroom with stomach pains on May 21, 2007.
She testified she didn't know she was pregnant until she delivered the baby in the toilet. She said the infant was blue and not moving, so she thought the boy was dead. She became scared and left the store without telling anyone what happened.
A female shopper in the bathroom found a tiny purple hand sticking out of the toilet and alerted staff. The store's manager grabbed a foot and pulled out the baby. Paramedics rushed the child to hospital and he was released a week later.
A doctor testified it was medically possible Halkett didn't know she was pregnant and, because she had such a speedy labour, the baby entered the world in a shock-like state. He added that the baby, about one month premature, probably survived because the cold water in the toilet prevented damage by slowing down body functions and conserving blood supply.
Halkett testified that when she learned her baby was alive, she wanted to see him and told police the truth. The boy was placed in foster care but she was given regular visits.
— By Chris Purdy in Edmonton