BOSTON – Jim Carberry watched his wife starve herself to death in the final stretch of a long battle with a spinal tumor that left her unable to communicate, walk and breathe on her own.

Margie Carberry struggled through 16 years of cancer treatments and lived long enough to see her youngest of two daughters graduate high school, telling her family and doctors that she wanted to die after that.

But the ailing Natick woman survived another year, finally passing away in 2011.

“It was horrible watching her waste away in front of our children,” her husband said. “Before she passed, I promised her that if there was anything I could do to help another family avoid this, I would do it.”

Jim Carberry is now among dozens of advocates for physician-assisted suicide who continue to press their case on Beacon Hill despite years of failed efforts to legalize the controversial practice in Massachusetts.

Under a bill filed by Rep. Louis Kafka, D-Stoughton, and backed by 39 lawmakers — including Sen. Barbara L’Italien, D-Andover, and Reps. Lenny Mirra, R-West Newbury, and Lori Ehrlich, D-Marblehead — the state would join Vermont, Oregon and Washington in allowing assisted suicide for people with terminal illnesses.

Kafka, who has filed similar legislation four other times, said he keeps pushing the issue because of a constituent, Al Lipkind of Stoughton, who died in 2009 after a battle with cancer.

“It’s not a question of life versus death,” Kafka said. “This is about giving people with terminal illnesses the choice of dying with dignity, not allowing them to pass away under painful circumstances.”

A U.S. Supreme Court ruling in 1997 left the issue of physician assisted suicide largely up to states.

Since then 34 states have banned the practice, either at the ballot box or by legislative act.

But, in recent months, measures to legalize the practice have surfaced in at least a dozen states including California, Connecticut and Maryland.

Montana and New Mexico’s courts have ruled that physicians may prescribe lethal drugs to the terminally ill.

The debate nationally was rekindled following news accounts of Brittany Maynard, a 29-year-old California woman with brain cancer who moved to Oregon to end her life under the state’s “death with dignity” law.

Maynard, who posted social media vignettes explaining her decision, became a prominent spokeswoman for the “death with dignity” movement, replacing the controversial pathologist Jack Kevorkian, known as “Dr. Death,” who assisted in more than 130 suicides before dying from kidney problems and liver cancer in 2011.

Opponents to assisted suicide, who include medical and religious groups and disability advocates, argue that misdiagnoses are common.

Terminally ill patients suffer from depression, they note, and may irrationally decide to end their lives.

Anne Fox, president of the Massachusetts Citizens for Life, says Kafka’s legislation doesn’t have enough protections against possible abuse.

Patients could be influenced by family members, Fox said, or may shop for doctors to prescribe the lethal medications, even if they aren’t dying.

“Whichever way you feel about physician assisted suicide, this is a poorly written bill with very few safeguards,” Fox said. “It’s scary.”

Supporters counter that the legislation, modeled after Oregon’s law, has numerous safeguards including a prohibition to keep doctors from prescribing lethal drugs to people with depression or impaired judgment.

The bill would require patients to make two verbal requests for a doctor’s intervention at least 15 days apart, as well as a written request signed by two witnesses.

The measure follows a failed ballot three years ago that would have allowed the terminally ill to end their lives with medication prescribed by physicians. The referendum was narrowly defeated, with 51 percent voting against it.

Right-to-die advocates say they were heavily outspent at the last minute by a coalition of religious leaders, anti-abortion activists and conservatives who poured more than $2.6 million into an aggressive campaign. By comparison, advocates spent only about $700,000 on TV ads.

“They really distorted the message,” said Marie Manis, campaign manager for the Massachusetts chapter of the national group Compassion and Choices, which put the question on the ballot. “But we’ve been out there trying to educate people and many seem to understand the issue now. There’s a lot of momentum.”

Methods of physician-assisted suicide vary by state but typically involve a prescription. Doctors are required to notify patients of alternatives like hospice care and wait at least 48 hours after receiving a written request from a patient.

In Washington, 173 people requested prescriptions for lethal medications in 2013, and 159 used them, according to the state’s Department of Health. In Oregon, 155 people obtained prescriptions, and 105 used them in 2014. Vermont hasn’t reported any assisted suicides under its law.

L’Italien, a longtime supporter of physician-assisted suicide, said she believes support for measure is growing. Last year, a poll conducted by Purple Strategies, a bipartisan polling firm based in Washington, D.C., found more than 70 percent of Massachusetts voters support giving terminally ill patients “control over end of life choices.”

“People have the absolute right to make these sorts of choices about their own lives,” L’Italien said.

Kafka said he expects an uphill battle to pass the legislation but that won’t stop him.

“It’s always a tough battle with an issue like this,” he said. “But support is growing, because a lot of people have had family members or friends suffer a painful death who would have benefited from such a law.”