A 25-year-old British Columbia woman is challenging Canada’s new assisted-dying legislation, arguing that the law’s requirement that death be “reasonably foreseeable” unfairly rules out patients with chronic and untreatable conditions.

Beth Lamb was diagnosed with spinal muscular atrophy in early childhood. She uses a wheelchair and relies on aides to help her with daily tasks, and she fears that, if her condition worsens, the nature of her progressive disease will disqualify her from an assisted death.

"My biggest fear is that if my condition suddenly gets much worse, which could happen any day, I will become trapped," the Chilliwack, B.C., woman said at a news conference on Monday.

"I feel a shadow looming over me. I know I could lose the ability to breathe well enough on my own and require a ventilator, which could affect my ability to speak."

According to the Liberal-backed legislation, doctors can only provide medical help if a patient’s death is reasonably foreseeable and if the patient’s condition is in an advanced state of irreversible decline.

Lawyer: Patients face ‘decades of suffering’

This requirement leaves out “a huge category of people,” including those with multiple sclerosis, Huntington’s disease, Parkinson’s disease and locked-in syndrome, according to a litigation expert from the law firm representing Lamb.

“These are people for whom death may be very far away, but they may be faced with the prospect of decades of suffering,” Grace Pastine, litigation director of the B.C. Civil Liberties Association, told CTV’s Power Play on Monday.

The B.C. Civil Liberties Association has been contacted by “many people” like Lamb over the past week with concerns about the new law, Pastine said. The association has called on other chronically ill patients to come forward and join the lawsuit.

“And we think it’s just really shameful that people like Julia have to come forward yet again, tell their stories yet again, when there are so many other things they should be focusing on in their lives. Because the Supreme Court of Canada granted them the right (to an assisted death) only to have the federal government take it away,” she said.

The Supreme Court of Canada struck down Canada’s ban on assisted death in 2015, and gave the federal government until June 6, 2016 to write a law. After plenty of back and forth between the House and Senate and a brief period of legal limbo, Bill C-14 received royal assent on June 17.

The constitutional challenge has been filed to the B.C. Supreme Court, and Pastine expects it will make its way up the justice system all the way to the Supreme Court of Canada.

“We’re just calling on the government to make this process as quick as possible. We would like to seek a speedy trial. We do not want sick and suffering Canadians to have to endure another incredibly long wait,” she said.

Wilson-Raybould: Law is ‘the right approach’

But Justice Minister Jody Wilson-Raybould said she is confident that the newly minted law is fair and constitutional.

"It represents the right approach for Canada at this important time in our country's history by striking the balance between personal autonomy for those seeking access, protection of the vulnerable, and respect for the conscience rights of health-care providers," Wilson-Raybould said.

Without access to an assisted death, patients like Lamb could be forced to leave the country to find the help they need, Pastine said. Switzerland offers assisted deaths to foreigners, but travelling overseas isn’t always an option.

“For some people, that might be a possibility. For others, it’s simply too expensive, they’re too sick, they don’t want to die away from their families, as I think any of us could understand,” she said.

With files from The Canadian Press