An infamous murderer who has spent more than 42 years in jail for his crimes has been denied leave to appeal against his life sentence by the state's highest court.

Kevin Crump, 66, has been in jail since 1973 for the rape, torture and conspiracy to murder of housewife Virginia Morse, 35, and the shooting murder of itinerant worker Ian Lamb, 43.

Crump and his co-offender Allan Baker were sentenced before the so-called "life means life" legal reforms in NSW - a time when criminals sentenced to life in prison were generally released on parole after serving an average of 11 to 12 years.

In 1997, Crump's sentence was re-determined to be a minimum of 30 years, expiring on November 12, 2003, with a maximum of life imprisonment, after Justice Peter McInerney found that he would not represent a danger to the community if released.

But, soon after, the NSW government reacted to pressure from sections of the public and the media by changing the law to ensure Crump and nine others were virtually never to be released on parole.

As a consequence, Crump has remained in jail even though he was eligible for parole 11 years ago.

Having tried unsuccessfully to have the government's reforms overturned in the High Court, Crump applied for leave to appeal against Justice McInerney's 1997 decision.

Appearing via video-link in the NSW Court of Criminal Appeal last November, Crump said he was representing himself in court because he was unable to get Legal Aid assistance and apologised several times for "not having me paperwork in order".

He told Justices Anthony Meagher, Geoffrey Bellew and Stephen Rothman: "I believe the sentence I received is over the limit of what I should have received.

"I believe that I should never have received a life sentence because it was not in the worst category of murder cases."

Crown Advocate Natalie Adams, SC, opposed Crump's application.

Ms Adams said that, even if Crump won the right to be re-sentenced, the effect of the 1999 Crimes (Sentencing Procedure) Act was that whatever non-parole period the appeal judges thought appropriate, the court would still have to impose a head sentence of life, which was what he already has.

On Friday, the NSW Court of Criminal Appeal refused Crump's application, meaning that his appeal will not even make it to a court hearing.

The three-judge appeal panel found that, while the circumstances of Crump's case were "exceptional", there was "a public interest in the avoidance of delay in the bringing of appeals against sentence and in ensuring the outcome of finality in sentencing litigation".

The only avenue remaining to Crump to avoid spending the rest of his life in jail - or at least until he is too old and incapacitated to be capable of causing harm - is to appeal against Friday's decision to the High Court.

Crump and Baker killed Mr Lamb at Narrabri on November 4, 1973, by shooting him four times to the head.

Soon after, they abducted Mrs Morse at her homestead, subjected her to 22 hours of atrocities including sexual assault, before shooting her once they were across the border in southern Queensland. They threw her body into a billabong.

with Louise Hall