Judges and juries weighing murder charges against a mother accused of killing her infant will still be allowed to apply the lesser charge of infanticide, Ontario’s top court has ruled.

The Ontario Court of Appeal denied an appeal by the Crown in the case of a Guelph, Ont., woman convicted of infanticide after smothering two of her children.

The case marks the first time a Canadian appellate court has examined infanticide provisions in the Criminal Code in detail.

The woman, who can only be identified as L.B., strangled an infant son in 1998, when she was 17. Another infant son died in a similar fashion in 2002.

In both cases, L.B. was originally charged with first-degree murder, which carries a mandatory life sentence. But she was convicted of infanticide, which is defined as a woman wilfully killing her newly born child when her mind is disturbed as a result of childbirth. A conviction carries a five-year sentence.

The Crown appealed the Superior Court’s decision, arguing the judge erred in allowing L.B. to be convicted of the lesser charge. It had argued that infanticide should only be used as a separate charge and not as a defence against the higher charge of first-degree murder.

The three-judge panel interpreted the Criminal Code to say infanticide can be both an offence a woman can be charged with and a partial defence a woman can use against a murder charge.

Wednesday’s decision means Canada’s infanticide provisions of the Criminal Code, which are more than 60 years old, will remain, pending any appeal to the Supreme Court of Canada.

In rendering its decision, the Appeal Court said: “Treating infanticide as a partial defence to murder is consistent with the distinction drawn between infanticide and murder by Parliament. … Eliminating infanticide as a partial defence effectively allows the Crown to remove the distinction between infanticide and murder through the exercise of its charging discretion.”

The case also drew attention to the issue of post-partum depression, which can affect up to 70 per cent of new mothers.

The Women's Legal Defence and Action Fund, known as LEAF, intervened in the case, arguing the Criminal Code's infanticide provisions should remain intact. LEAF legal director Joanna Birenbaum told CBC News the law, as it exists, gives the court the essential option of an offence that recognizes the desperate situation many women face after giving birth.

"LEAF is pleased with the decision," Birenbaum said. "The women who commit infanticide in Canada tend to be young, poor, socially isolated and without adequate social and economic supports to cope with childbirth or caring for a child."

"Infanticide is a very serious crime, but it is a crime which recognizes the reduced culpability of women whose minds are 'disturbed' due to the interaction of these complex factors related to childbirth."

With files from The Canadian Press