Senators voted Wednesday to expand Canada's assisted dying regime to allow individuals who fear losing mental capacity to make advance requests for medical help to end their lives.

The amendment to Bill C-7 was approved by a vote of 47-28, with eight abstentions.

Sen. Pamela Wallin, a member of the Canadian Senators Group who proposed the amendment, argued that the law currently traps Canadians in "a perverse diagnosis lottery." Someone diagnosed with incurable cancer can receive an assisted death, she noted, but someone with Alzheimer's disease or other cognitive-impairing conditions may have already lost the mental competence to consent by the time they're diagnosed.

"As someone with a history of dementia in my family, I seek the peace of mind that an advance request and consent to it will provide," Wallin told the Senate.

"I am certainly not alone in this belief. The majority of Canadians have come to the same conclusion."

Giving people the chance to make written advance requests, spelling out when they would want to receive an assisted death, "would give those who are fearful of losing their conscious capacity the certainty that they can access MAID (medical assistance in dying) before they reach a place where consent may not be possible," Wallin said.

Bill C-7 would expand assisted dying to people whose natural death is not reasonably foreseeable. It would establish more relaxed eligibility rules for those who are near death, including a limited form of advance request, and more stringent rules for those who are not.

For those near death who have consented to and been approved for an assisted death, it would waive the requirement that they be able to give final consent immediately before the procedure is performed. That measure is intended to deal with situations in which a person loses mental capacity after being approved for an assisted death.

Wallin's amendment would extend that waiver of final consent to people who are not near death.

Even many of the senators who opposed Wallin's amendment were sympathetic to her objective.

Sen. Marc Gold, the government's representative in the Senate, choked up as he expressed his admiration for Wallin's "passionate and reasoned and reasonable" advocacy for advanced requests.

But he argued that the Senate has not studied the issue because it wasn't included in the bill. During committee hearings, he said senators heard repeatedly that even minor changes to the assisted dying regime shouldn't be rushed and must be considered thoroughly.

"We simply have not properly considered the ramifications and effect of this proposal and it would be — and I say this respectfully because I am touched and moved by it — it would be irresponsible to introduce this as an amendment to C-7," Gold said.

However, Sen. Frances Lankin, a member of the Independent Senators Group, countered that every province and territory already has regulations in place to allow people to make advance directives about end-of-life treatment, including refusing heroic efforts to keep them alive on feeding tubes, for instance.

"This amendment ... builds on top of all of that," Lankin argued.

The current law, Lankin said, allows her to say in advance, "I don't want any intervention under these conditions, I want to die." But it does not allow her to say in advance that she would prefer an assisted death under those same conditions, rather than to die by starvation and thirst.

"This makes no sense to me."

Sen. Jim Munson, a member of the Progressive Senate Group, said he had intended to abstain on Wallin's amendment. But after listening to the debate, which included senators recounting their harrowing experiences with family members with dementia who died in agony, he concluded: "I think sometimes the Senate has to take the initiative and has to force the debate."

Senators rejected another amendment, proposed Wednesday by Conservative Senate leader Don Plett, which would have made it a crime for medical practitioners to discuss assisted dying with a patient unless the patient raised the subject first.

Plett argued that his amendment would help alleviate the concern of people with disabilities who've complained about feeling pressured to receive an assisted death.

But other senators argued that doctors and nurses have a professional obligation to discuss all available options with their patients.

Plett's amendment was defeated by a vote of 66-18, with one abstention.