WHEN my mother-in-law was in the final, harrowing throes of pancreatic cancer, she had only one good day, and that was the day she smoked pot.

So I was heartened when, at the end of last month, the governors of Washington and Rhode Island petitioned the Obama administration to classify marijuana as a drug that could be prescribed and distributed for medical use. While medical marijuana is legal in 16 states, it is still outlawed under federal law.

My husband and I often thought of recommending marijuana to his mother. She was always nauseated from the chemotherapy drugs and could barely eat for weeks. She existed in a Percocet and morphine haze, constantly fretting that the sedation kept her from saying all the things she wanted to say to us, but unable to face the pain without it. And this was a woman who had such a high tolerance for pain, coupled with a distaste for drugs, that she insisted her dentist not use Novocain and gave birth to her two children without anesthesia. But despite marijuana’s power to relieve pain and nausea without loss of consciousness, we were afraid she would find even the suggestion of it scandalous. This was 1997, and my mother-in-law was a very proper, law-abiding woman, a graduate of Bryn Mawr College in the 1950s. She’d never even smoked a cigarette.

But then an older family friend who worked in an AIDS hospice came bearing what he said was very good quality marijuana. To our surprise, she said she’d consider it. My husband and I ”” though we knew nothing about marijuana paraphernalia ”” were dispatched to find a bong, as the friend suggested water-processing might make the smoking easier for her. We found ourselves in a head shop in one of the seedier neighborhoods in New Haven, where my husband went to graduate school, listening attentively to the clerk as he went over the finer points of bong taxonomy, finally just choosing one in her favorite color, lilac.

She had us take her out on the flagstone patio because she refused to smoke in her meticulously kept-up house. Then she looked about nervously, as if expecting the police to jump out of the bushes. She found it awkward and strange to smoke a bong, but after a few tries managed to get in two and a half hits.

And then she said she wanted to go out to eat.

For the past month, we’d been trying to get her to eat anything: fresh-squeezed carrot juice made in a special juicer, Korean rice gruel that I simmered for hours, soups, oatmeal, endless cans of Ensure. Sometimes she’d request some particular dish and we’d eagerly procure it, only to have her refuse it or fall back asleep before taking a bite. But this time she sat down at her favorite restaurant and ordered a gorgeous meal: whitefish poached with lemon, hot buttered rolls, salad ”” and ate every bite.

Then she wanted to go to Kimball’s, a local ice cream place famous for cones topped with softball-size scoops. The family had been regular customers starting all the way back when my husband and his brother were children, but they hadn’t been there since her illness. My husband and I shared a small cone, which we could not finish, and looked on in awe as my mother-in-law ordered a large and, queenishly spurning any requests for a taste, polished the whole thing off ”” cone and all ”” and declared herself satisfied.

We were of course raring to make the magic happen again, but it never did. The pot just frightened her too much. She was scared her friend would be arrested for interstate drug trafficking, that my husband and I would be mugged in New Haven; she was afraid she’d become addicted or (à la “Reefer Madness”) go insane. It was difficult watching her reject something that had so clearly alleviated her nausea and pain and ”” let’s admit it ”” lightened her mood in the face of the terrible fact that cancer had invaded nearly every essential organ. And it was even worse to watch her pumped, instead, full of narcotics that made her feel horrible. The Percocet gave her a painfully dry mouth, but even ice chips made her heave. We were reduced to swabbing her lips with little sponges dipped in water, and waiting out her agony.

My husband and I have dredged up the memory of that one good day many times since, how she smiled and joked, for the last time seeming a little like her old self.

After the funeral, saying goodbye to all the family and friends, supervising the removal of the hospital bed, bedpans and related paraphernalia, one of the last things my husband and I did, under the watchful eyes of the hospice nurse, was destroy her remaining Percocets. We opened the multiple bottles and knelt in front of the toilet to perform this secular water rite, wishing there had been other days, other ways, a softer way for her to leave us.