Lee Carter and her husband Hollis Johnson had filed a lawsuit challenging the law in 2011 after Carter's mother unsuccessfully sought to get assistance in dying, the Vancouver Sun reported Thursday.
The couple was later joined in the suit by Gloria Taylor, who suffered from amyotrophic lateral sclerosis, known as Lou Gehrig's disease. ALS gradually shuts down all the body's system's, including breathing. She died in 2012.
The British Columbia Supreme Court overturned the law and ruled a new law must be introduced to provide the option of getting assistance in dying when the person's pain was unbearable.
The province's Court of Appeals reversed the B.C. Supreme Court's ruling in 2012 in a 2-1 decision.
Carter's mother, Kathleen Carter, died in 2010 from lethal injections at a suicide clinic in Switzerland.
Assisted suicide is legal in four European countries. New Mexico this week became the fifth U.S. state to legalize it.