A former staff nurse serving at least 30 years behind bars for the murder of four patients at two Leeds hospitals was given the go-ahead to challenge his conviction today.
But Court of Appeal judges who granted Colin Norris leave to appeal emphasised that it did not mean they had formed any view "on the merits of the appeal".
Lord Justice Aikens, sitting with two other judges in London, said the court had "considered very carefully" the papers in the case and announced that "we can say at this stage that we grant leave".
He went on to say: "However... I will emphasise that does not mean that we have formed any view on the merits of the case, but we do think it is a suitable case where leave should be granted."
Norris was present in the dock of the court for the proceedings.
Now that leave has been given, his QC, William Clegg, will present the grounds of appeal to the judges in a hearing expected to last a day.
Mr Clegg said the grounds "all focus" on directions given by the trial judge.
Norris, from Egilsay Terrace, Glasgow, was jailed for life in March last year after being convicted of killing the vulnerable women in 2002 by giving them massive doses of insulin while working at Leeds General Infirmary and St James's Hospital.
At Newcastle Crown Court, Mr Justice Griffith Williams told him: "You are, I have absolutely no doubt, a thoroughly evil and dangerous man."
Norris, then 32, was convicted of four counts of murder and one of attempted murder following a lengthy trial.
He was convicted of killing Doris Ludlam, 80, Bridget Bourke, 88, Irene Crookes, 79, and Ethel Hall, 86.
Jurors also found him guilty of trying to kill Vera Wilby, 90.
Police began an investigation after a doctor noticed in November 2002 that Mrs Hall had slipped into a hypoglycaemic coma despite not being a diabetic.
Blood tests showed she had insulin levels 12 times the norm, and she died three weeks later.
It is not known if the judges will give a ruling at the completion of legal submissions by Mr Clegg and on behalf of the Crown or will reserve their decision to a later date.