The danger with that, Marker said, is that because assisted is less expensive than the other treatments, it would be more attractive to insurance companies.
That's what Barbara Wagner, a 64-year old Oregon woman, said happened to her. In 2008 she said she was denied $4,000-a-month treatment for her lung cancer, but told by the state health insurance company that she would be reimbursed for a $50 physician-assisted death.
"It was horrible," Wagner, who has since died, told ABCNews.com. "I got a letter in the mail that basically said if you want to take the pills, we will help you get that from the doctor and we will stand there and watch you die. But we won't give you the medication to live."
Critics were up in arms over the indignity of her unsigned rejection letter. Even those who support Oregon's law were upset.
Marker said because assisted suicide is cheaper, dying patients are encouraged to end their lives. So, too, might family members instill a sense of guilt in the terminally ill.
"This equal treatment leads to the subtle and unintended expectation of a course to consider because it makes it easier on the family," she said. "It's not just a political matter, it's psychological and familial."
Clay Baxter, whose father is immortalized in this Supreme Court challenge, argues that good legislation in a Montana Death With Dignity Law could safeguard against that kind of problem.
And his father's slow, painful death is a reminder of the need for giving the dying more choice from their physicians, he said.
"Personally, I don't think I could do it," said the 52-year-old who works in information technology at a North Dakota hospital. "But I haven't walked a mile in his shoes and lived year after year with this. How much can you take?"
His sister, Roberta King, said she agrees.
"The lawsuit was one of the things my father was passionate about in the end," she said. "He wanted to stay alive to get it done."
"I got involved because I knew how much it meant to my dad," King said.
"Everybody should have the option," she said. "I wished my father had had the option -- the comfort of being able to have some control. That was what bothered him the most."