Diane Rehm and her husband John had been married for 54 years when he knew he didn’t want to live another day.

His Parkinson’s disease had become unbearable. “He just kept getting weaker,” the NPR host told NBC News. “We called in the doctor and John said to him: ‘I am ready today.’ He said ‘I can no longer use my legs, I can no longer use my arms, I can no longer feed myself.’ And knowing with Parkinson’s it is going to get worse rather than better, he said ‘I wanted to die.’” He asked the doctor for help.

The answer they got surprised and disappointed both of them. “The doctor said ‘I cannot do that legally, morally or ethically’,” Rehm said. “He said ‘I don’t disagree with your wish that you could die with the help of a physician but I cannot do it in the state of Maryland.’”

John Rehm had to deliberately die by dehydration. It took nine days.

“John said he felt betrayed,” Rehm said. He said, ‘I felt that when the time came, you would be able to help me.’”

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It’s just the type of death the advocacy group Compassion & Choices, among others, has been fighting to prevent. Instead, John Rehm should have had the option of an assisted death, the group says. They call for "aid in dying" — allowing mentally competent, terminally ill adults to request life-ending medication from a doctor for a peaceful and painless death. It's legal in several states, but not Maryland.

John Rehm met the definition, says Diane Rehm, a nationally syndicated talk show host for WAMU-FM in Washington.

“Both of us had agreed that when the time came, we would be there for each other in whatever way was necessary,” she said. “So when he made up his mind, that was it.”

"He simply decided the end had come and he did not want to carry on this way."

She wasn’t happy about it, but understood his decision. He’d been in assisted living since November of 2012. “That was something we had both agreed we never wanted but at that point he had started falling and I couldn’t lift him,” said Rehm.

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By June of this year, John was very frail. There’s no cure for Parkinson’s, and the few available treatments eventually stop working. “He was so brave,” Rehm said. “He simply decided the end had come and he did not want to carry on this way. He could no longer feed himself, he couldn’t shower alone, he couldn’t stand alone.”

The only option, his doctor told him, was to refuse all food and water. It’s not an easy way to die, as it takes anywhere from a few days or a few weeks to succumb to dehydration. It can be very painful, causing headaches, leg cramps and delirium.

John Rehm’s doctor kept an eye on him, administering low doses of morphine to control the discomfort. “He did not seem to feel pain,” Rehm said. “We kept putting lotion on his lips and using tiny little sponges in his mouth to keep him comfortable.”

It wasn’t easy to watch. “I wanted to take applesauce and put it in his mouth,” Rehm said. “But you can’t do that. You have to respect someone else’s wishes. You have to honor his desires. And he was finished with life. He said ‘I am looking forward to the next journey’,” she added.

Polls show that 65 percent or more of the U.S. population supports having an option available to help people choose a quicker, more painless death, Compassion & Choices says. This is different from assisted suicide or euthanasia, the group stresses. “Assisted suicide is a crime in many states, including Oregon and Washington, where aid in dying is legal,” the group says.

Assisted dying is also legal in Vermont and Montana. Several other states have considered the matter.

"I have no doubt that he was terminally ill and if he was in Oregon he would have qualified for aid in dying," said Barbara Coombs Lee, president of Compassion & Choices.

"He should have had better choices."

“We do not let our little animals suffer and people shouldn’t have to suffer.”

In the United States, there's strong opposition, Coombs Lee says. "There is a vocal and politically strong minority that opposes it vehemently," she said. "They have all the power in the legislatures. The combination of organized medicine and organized religion is an extremely powerful combination in the halls of our nation’s legislatures."

Compassion & Choices says it doesn't support euthanasia or "mercy killing," "because someone else — not the dying person — chooses and acts to cause death." What is called euthanasia and is legal in some European countries more closely resembles what the group calls aid in dying.

It would allow a doctor to prescribe a lethal dose of drugs for a patient to take as he or she chose. “I would like to, in every state across the country, in every city, in every county, I would very much like to see a justification, an allowance, for aid in dying,” Rehm said.

“We do not let our little animals suffer and people shouldn’t have to suffer.”

Such a method could help patients ensure that loved ones are with them if they wish. As it happened, Rehm wasn’t there in her husband’s very last moments on June 23rd.

“I spent the night there Sunday night the 22nd because I was afraid he was going to die that night and I didn’t want him to die alone,” she said. She and their dog Maxie slept beside John’s bed.

“I will hopefully someday, with the help of a kind physician, be able to end my life when I choose."

“When the caregiver arrived at about 7:30 in the morning I said ‘I’ll run home and feed Maxie and take a shower and I’ll be back’.” A doctor called her soon after and said John, who was unconscious by this time, would likely die within the next 24 hours. But before she could get back, the caregiver called. John Rehm had died. “I got there 20 minutes too late,” Rehm said.

Rehm doesn’t want that type of uncertainty for herself. “I will hopefully someday, with the help of a kind physician, be able to end my life when I choose,” she said.

“I think there are so many reasons why people choose to end their lives and I am not talking about people who are desperate, who are miserable and lonely. I am talking about people who have lived their lives and are satisfied with what they have had and are really ready to let go,” she added.

“I just think we ought to be able to create that space for ourselves where we can choose to die with dignity and with the aid of a physician.”

As for her husband, Rehm said, “I will love him and miss him forever.”