Jeremy Bamber and two other murderers will have their appeal that keeping them behind bars for the rest of their lives is a breach of their human rights heard by the Grand Chamber of the European Court of Human Rights.
Bamber received a life sentence for shooting dead five members of his family in Essex in 1986.
He has always protested his innocence and claims his schizophrenic sister Sheila Caffell shot her parents and her six-year-old twin sons before turning the gun on herself.
Bamber has previously attempted to get his conviction overturned but it has been upheld several times.
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Among those expected to attend the ceremony will be former US President Bill Clinton and ex-Northern Ireland first minister Peter Robinson.
Five people have been killed and 40 injured after a car and knife attack in London on Wednesday.
A wet, wintry night in places with rain and hill snow slow to move away from southern Scotland and northern England.