Dr. Eric Kress has been a family physician for 26 years, but he will never forget the terminally ill patient who called him a "coward" for hesitating to prescribe him lethal medication that would ease his pain and help him die.
The man was a "rugged individualist," dying a "hard death" from amyotrophic lateral sclerosis, or ALS, a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord and eventually ends in death.
"This once-strong man had been reduced to 120 pounds of skin and bone," said Kress, 50, of Missoula, Mont. "He could not swallow or walk. He would often be found weeping and bemoaning the miserable fate that had befallen him. He begged his wife to end his suffering."
Weeks later the man took his own life with pain-killing medication he had stockpiled, but Kress never forgot his words. Since then, he has helped three other patients end their lives -- all with the consent of their families.
In 2009, the state Supreme Court ruled narrowly in Baxter v. Montana that state law protects doctors from prosecution when helping terminally ill patients die, but it fell short of addressing the larger question of whether physician-assisted suicide was a guaranteed right under the state constitution.
But on Thursday, the Montana Senate gave a preliminary nod to a House-passed bill that would criminalize physician-assisted suicide. If it passes two more readings today and Saturday, HB 505 could soon be on the desk of Gov. Steve Bullock, a Democrat.
Kress has become the public face of that raging debate, testifying in the legislature and writing an April 7 column in the local newspaper, the Missoulian.
"This man affected me," Kress wrote about the man with ALS. "What kind of man or doctor am I? Am I just going to sit idly by watching a proud man suffer and die, or am I going to be brave and do what it takes to help people at the end of life? I spent many sleepless nights pondering this question."
Now, Kress could face 10 years in prison if he continues to help patients die.
Supporters of HB 505, such as Montanans Against Assisted Suicide, argue that if the bill is enacted "there will be a clear statement going forward that assisted suicide is not legal."
"The issue deserves the governor's attention, and he needs to address it," said organization coordinator Bradley D. Williams.
The move comes as at least five states are considering legalizing the practice: Vermont, New Jersey, Kansas, Hawaii and Massachusetts. Already, both Oregon and Washington state have so-called Death With Dignity laws in place.
Kress told ABCNews.com that he would not continue to help terminally ill patients die if the bill becomes law. "I am not a physician that wants to go to jail," he said.
"I always stress that the issue of suicide is a very small part of my practice," he said. "Every day I see depressed patients, and I spend so much time with them figuring out who is suicidal and who isn't than with aiding in dying. At times, I've had the privilege, but the majority of my work is preventing them from dying."
If HB 505 becomes law, it would gut the Baxter ruling, according to Compassion and Choices, the advocacy group that represented Robert Baxter, a truck driver and once avid outdoorsman whose health was ravaged for 12 years by cancer. He died in 2008, at nearly the same hour the First District Judicial Court upheld his right to seek help in dying.
"My dad said to us that he didn't want to die, but cancer was killing him," his daughter, Roberta King, told ABCNews.com. "Eventually, he was wasting away piece by piece. … He did fight it, but he couldn't fight any longer.
"He really felt it was a personal choice, and no one else's business, and that's what he was fighting for," she said. "He wanted to make it legal so family and those left behind would not be prosecuted."
In states where the practice is legal, doctors prescribe the quick-acting drug Seconal, a barbiturate once used as a sleeping pill, which was responsible for the overdose deaths of actresses Judy Garland and Marilyn Monroe. A terminal patient's wishes must be confirmed by two doctors, and the patient must self-administer the drug.
Both sides of the issue have run powerful ads. More than 100 doctors in favor of HB 505 use cancer survivor Jeanette Hall of King City, Ore., to deliver their message. Her state has allowed doctors to prescribe lethal medication in cases of terminal illness since 1997.
"In 2000, I was diagnosed with cancer and told that I had six months to a year to live. I did not want to suffer, and I did not want to do radiation," she says in the ad. "If my doctor believed in assisted suicide, I would be dead."
Disability groups have also supported the bill on moral grounds. Others argue that legalizing physician-assisted suicide would lead to elder abuse.
An ad by Compassion and Choices includes an image of Kress with testimony from other doctors who oppose HB 505. They argue that helping terminally ill patients of sound mind to die without pain is an "essential act of medical care."
Kress said such a law would undermine "one of the most sacred relationships," that between a doctor and patient.