Dr Jack Kevorkian, who claims to have helped 130 people to commit suicide, is now on trial for the murder of a paralysed man whose family sought his aid. He faces life imprisonment if found guilty.
The physician, sometimes called "Dr Death", is conducting his own defence in the trial in Pontiac, Michigan, hoping to use the courtroom as a platform for his controversial views on euthanasia and so-called "mercy killing". But Judge Jessica Cooper is preventing him from using the victim's sufferings as a defence in a murder charge.
The judge also warned him when he dismissed his lawyers that he risked spending the rest of his life in prison. "There's not much of it left," replied the 70-year-old retired pathologist, who has said he will starve himself to death if sent to prison.
He has been charged with the murder of Mr Thomas Youk, whose death from injection of lethal drugs was shown on television last year. Mr Youk (52) was suffering from a progressive sclerosis known as "Lou Gehrig disease" that leaves victims unable to speak, swallow or move.
Viewers of the CBS programme, 60 Minutes, saw Mr Youk in his wheelchair, mumbling responses to Dr Kevorkian, who then appeared to administer three injections. The doctor sent the tape to the TV programme and was interviewed, commenting on the death and challenging the authorities to prosecute him.
"I've got to force them to act," he told the interviewer.
"You killed him," the interviewer, Mike Wallace, replied.
"I did, but it's gonna be manslaughter, not murder," the doctor said. "But it doesn't bother me what you call it. I know what it is."
Now facing the charge of first-degree murder, Dr Kevorkian has compared himself with an executioner or soldier doing his duty. What he did to end Mr Youk's life was "another form of excusable homicide", he said. "I despise a human being dying in my hands," he told the judge. "But my intent isn't to kill the person. I thought it was my duty as a physician to do this."
This is his fifth trial since he began helping sick persons to commit suicide. Three ended with acquittals on manslaughter and a fourth as a mistrial.
Juries in these earlier trials on the charge of assisting suicide were swayed by Dr Kevorkian's description of the sufferings of the victims, who administered the lethal injection themselves with the help of the doctor's "suicide machine".
In the case of Mr Youk, who was too helpless to inject himself, the prosecutor told the court: "Jack Kevorkian killed Tom Youk and Jack Kevorkian did not have the right to kill."
The prosecution then played the videotape of Mr Youk's death to the jury.
Since Dr Kevorkian's last trial, Michigan has voted to reject a proposal to legalise assisted suicide. Oregon is the only state in the US which has legalised it.