Three senior judges today threw out an appeal on behalf of Ruth Ellis - the last woman to be hanged in Britain - saying it was "without merit".
They said that Ellis was properly convicted of murder according to the laws at the time she shot her lover in 1955.
The judges were critical that the case had been referred to them by the Criminal Cases Review Commission, the legal watchdog which reports on possible miscarriages of justice.
Lord Justice Kay, giving the ruling of the court, said: "We have to question whether this exercise of considering an appeal so long after the event, when Mrs Ellis herself had consciously and deliberately chosen not to appeal at the time, is a sensible use of the limited resources of the Court of Appeal."
Lawyers acting for Ellis's sister, Muriel Jakubait, asked judges to quash the murder conviction and substitute a verdict of manslaughter on the grounds of provocation and/or diminished responsibility.
The 28-year-old nightclub hostess was hanged in 1955 for killing racing driver David Blakely as he left the Magdala pub in South Hill Park, Hampstead, north London.
The appeal judges ruled that the defence of diminished responsibility was not available at that time and for provocation to succeed it had to be proved that Ellis was subjected to an immediate affront and all her normal self-control had been lost.
Mrs Jakubait said after the ruling: "I can't believe it after all these years. What is so different about Ruth than anyone else?
"The whole thing seems very unfair and I am never going to give up over this until I am taken from this earth.
"Ruth always said she hoped the truth would come out one day and now, more than 50 years later, I hope to do something about all the lies that have been written about her."
She said she was working on a book, Ruth Ellis, The Untold Story, which she hoped would be published next year.