Double killer John Pierson, who was jailed for life for shooting his sleeping mother and father at their remote farm at Oswestry, North Wales, in September 1984, has been given the go-ahead to take a test case challenge over minimum sentences to the House of Lords.
Pierson is serving two mandatory life sentences imposed on him at Chester Crown Court in July 1985, and in 1993 the Home Secretary Michael Howard increased the minimum sentence he should serve from 15 years to 20 years.
Last November Mr Justice Turner ruled in the High Court that the Home Secretary was wrong. In December, however, Mr Justice Turner's ruling was overturned in the Court of Appeal by Sir Thomas Bingham, Master of the Rolls, along with Lords Justices Neill and Hirst. They upheld the Home Secretary's decision to increase Pierson's minimum sentence. They ruled that it could not be "stigmatised as irrational".
Now though the Law Lords have given Pierson leave to mount a test case to challenge the Court of Appeal decision.
When the case reaches them, they will rule on the length of time Pierson should be kept behind bars for the purpose of retribution and deterrence.
The Lords will be asked to hold that the Home Secretary acted in neither a rational or fair manner.
The murders Pierson committed have been described as both "horrifying and apparently motiveless".
The appeal judges in reaching their decision stressed that they were not concerned about the length of Pierson's sentence, but that their decision would be based on the lawfulness of the decision that the Home Secretary took.