Yorkshire Ripper Peter Sutcliffe is to learn the outcome of his plea not to have to spend the rest of his life behind bars.
A judge in the High Court in London will announce his decision on an application by the serial killer to have a minimum term set which will give him the chance of parole.
Now known as Peter Coonan, the 63-year-old former lorry driver, from Bradford, West Yorkshire, was convicted at the Old Bailey in 1981.
He received 20 life terms for the murder of 13 women and the attempted murder of seven others in Yorkshire and Greater Manchester.
A judge recommended that he serve a minimum of 30 years behind bars.
His name was not on a Home Office list, published in 2006, of 35 murderers serving "whole life" sentences and he was given no formal minimum term - which is the least a prisoner must serve before becoming eligible to apply for release on parole.
He is currently being held in Broadmoor top security psychiatric hospital after being transferred from prison in 1984 suffering from paranoid schizophrenia, and in 2006 he was said in a report to pose a "low risk of reoffending".
It was on July 5 1975, just 11 months after his marriage, that he took a hammer and made his first attack on a woman.
Sutcliffe is said to have believed he was on a "mission from God" to kill prostitutes - although not all of his victims were sex workers - and was dubbed the Yorkshire Ripper because he mutilated their bodies using a hammer, a sharpened screwdriver and a knife.
In setting his tariff, the High Court is expected to take account of the gravity of his crimes, whether or not he has made "exceptional" progress in custody, the state of his mental health and any representations from him, his victims or their families.