Ontario's top court has dismissed a legal challenge brought by a Toronto-area family that fought to keep their daughter on life support after she was declared brain-dead.

But the court of appeal declined to rule on whether accommodations for religious beliefs should be applied to the criteria used to determine that someone has died.

In a unanimous decision, the appeal court says that while death is not defined in law federally or provincially in Ontario, common law considers someone dead when there is the irreversible cessation of either cardiorespiratory or brain function.

However, it says there is not enough information before the court to settle the issues that form the crux of the case, including whether those criteria constitute a violation of the right to freedom of religion.

The court also noted that the woman at the heart of the challenge, Taquisha McKitty, has since died according to both neurological and cardiovascular criteria, rendering the ruling moot.

It says the same questions will likely emerge in other cases, and lays out guidelines on how to assess those arguments in the future, adding the lower court judge in this case made several errors.

A Toronto-area family lawyer who had been closely following the case agreed that the decision will provide clarity to any family facing a similar situation.

"In cases now, a family could look at the McKitty case and know that it probably is futile to pursue litigation," said Lisa Feldstein.

The complex case "affirms the status quo," she added.