TORONTO -- The Canadian Medical Association hopes to play an integral role in crafting new right-to-die regulations if the Supreme Court of Canada strikes down the existing law that bans doctor-assisted suicide -- an act the organization now says may be "appropriate" in rare cases of extreme suffering.

The court is to deliver its judgment Friday on a challenge to the federal law that makes it a criminal offence to "counsel, aid or abet" another person to commit suicide.

Should the justices rule the law on assisted death and euthanasia is unconstitutional and needs amendment, "we feel pretty strongly that we want to be at the table" to help draft a new law and guidelines for physicians and patients, CMA president Dr. Chris Simpson said Thursday.

"We want to know how the rules would be applied," he said. "Would it be patients with only certain types of illness? What do we mean by terminal illness? How many doctors would have to approve? Would there be a period of sober second thought that would be imposed to make sure everybody is certain?

"And are we only going to allow people who themselves are competent to make the decision or are we going to allow substitute decision makers like family members to be involved in the decision if the patients are not competent, for example with dementia?"

The CMA has long opposed physician-assisted death, but a recent policy statement slightly altered that all-or-nothing position: "There are rare occasions where patients have such a degree of suffering, even with access to palliative and end-of-life care, that they request medical aid in dying. In such a case, and within legal constraints, medical aid in dying may be appropriate."

Assisted suicide has been a hot-button issue among the group's 80,000 members: a 2014 survey of 5,000 doctors found that while 45 per cent favoured legalizing physician-assisted death, 27 per cent said they would likely or very likely participate if the act was decriminalized.

At the CMA annual meeting in August, 91 per cent of delegates voted for a resolution that would let doctors follow their conscience if medically aided dying becomes legal.

The court challenge revolves around two B.C. women, now deceased, who wanted to end their "grievous and irremediable" illnesses with medical help. Gloria Taylor, who had a neurodegenerative disease, died of an infection. Kay Carter, then 89, travelled to Switzerland, where assisted suicide is allowed.

Taylor won a constitutional exemption in a lower court for a medically assisted death in 2012, but that was overturned in appeals. Last January, the Supreme Court of Canada agreed to settle the matter, re-evaluating the decision made in the 1993 Sue Rodriguez case.

Rodriguez, a B.C. woman with ALS, or Lou Gehrig's disease, had sought the legal right to end her life with a doctor's help. The High Court rejected her bid in a 5-4 ruling.

What the current nine-justice panel will decide is anyone's guess, but there are a few possibilities, said Erin Nelson, a professor at the University of Alberta specializing in health law.

The court could uphold the existing law, strike it down or rule that while a complete prohibition is unconstitutional, "thought should be given to how a partial ban on assisted suicide could be accomplished," she said from Edmonton.

Nelson thinks it's likely the court will strike down the law but then invalidate the decision for perhaps a year to give Parliament time to amend the legislation.

Should the existing law be overturned, it doesn't mean doctors would be required by law to accede to terminally ill patients' requests for help to end their lives -- but it would mean they couldn't be criminally prosecuted.

"The more challenging issue will be for the doctors as a profession to work out how they should approach whether or not they're going to help," she said, noting some terminal patients, or their loved ones, are sure to broach the subject with their doctors.

"Even if they don't feel that they want to be involved in helping patients ... it's going to be present in their practice in a way that just hasn't been the case until now."

Simpson said it's unlikely CMA members would support any measure that would compel an unwilling doctor to medically hasten the death of a patient or to refer the patient to a colleague who is willing.

"But I think we all recognize that if this does become part of the fabric of the country, it's important that it be made available to patients. Somehow we have to balance the right of physicians not to be involved ... but at the same time ensure there are enough people and enough places that are able to provide that service for patients if they choose it."