Alan Blythe, 52, of Runcorn, Cheshire, told Warrington Crown Court that he feared that his wife, Judith, might commit suicide if she was not able to take the illegal drug to alleviate her acute symptoms.
Mr Blythe, a cab driver, was acquitted of cultivating cannabis, cultivating it with intent to supply and supplying it. He was found guilty of possession and fined pounds 100.
He pledged after the trial that he would continue to break the law. "I have never stopped giving her the cannabis, and I never will," he said.
In evidence, Mr Blythe told the jury how his wife was diagnosed with MS in 1983, 15 years after they married, and her condition steadily deteriorated thereafter.
Prescription drugs did little to help, he said, and her main symptom - acute attacks of dizziness - culminated in a three-week period in 1989 when she was bedridden, virtually unable to move.
Mrs Blythe herself told the court on Thursday: "It was so severe that I wanted to die. I wanted someone to kill me. I felt as though I had been thrown into a bottomless pit at 100mph and I couldn't even move my eyeballs."
Afterwards, Mr Blythe said, his wife told him that she could not live through another similar attack. He told her that he would never help her die. But some time later she informed him that a friend of hers would be prepared to assist.
"She made it clear to me that she would never go through it again, very clear," he said.
It was two or three years later that Mrs Blythe experimented with cannabis, after reading a magazine article that suggested that it might have beneficial effects for MS sufferers.
The court was read evidence from Dr Roger Pertwee, of Aberdeen University, a leading expert on the effects of cannabis, who said the drug had been shown to relieve MS symptoms in six clinical trials.
Ten cannabis plants were found at the Blythes' home during a police raid in July last year, together with pots of cannabis bush heads and a variety of growing equipment.
The jury disregarded the judge's suggestion that Mr Blythe had failed to prove duress of circumstances for the charge of cultivation, but it accepted the advice in relation to possession.
After the verdict, Mr Blythe called for reform of the law which prevents doctors from prescribing the drug for MS patients.
The Multiple Sclerosis Society said that while it recognised that some people's symptoms were relieved by cannabis, it believed more research was needed to establish the drug's effectiveness and safety.
The Home Office said the Government was prepared to review the question of decriminalising cannabis for specific medical purposes if a scientific case was proven. But the British Medical Association said that current legislation made it unlikely that relevant research could be carried out in Britain.Reuse content