No medication made the pain bearable. A woman who had been generous and good-humored turned into someone hardly recognizable to her loving family: paranoid, snarling, violent.

Sometimes, she would flee into the California night in her bedclothes, "as if she were trying to outrun the pain," her older sister Anita Freeman recalled.

Ms. Martin fantasized about having her sister drive her into the mountains and leave her with the liquid morphine drops she had surreptitiously collected over three months — medicine that didn't relieve her pain but might be enough to kill her if she took it all at once. Ms. Freeman couldn't bring herself to do it, fearing the legal consequences and the possibility that her sister would survive and end up in even worse shape.

California's aid-in-dying law, authorizing doctors to prescribe lethal drugs to certain terminally ill patients, was still two years from going into effect in 2016. But Ms. Martin did have one alternative to the agonizing death she feared: palliative sedation.