Jeremy Bamber, who murdered five of his family members, and two other killers were told their whole-life tariffs amounted to a breach of human rights.
The European Court of Human Rights said whole-life sentences were "inhuman and degrading".
ITV News deputy political editor Chris Ship reports:
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The son Cecil the lion, whose 2015 killing prompted an international outcry, has also been fatally shot during a hunt.
Thickening cloud and rain stalling across Wales and southwest England through tomorrow
A parole board in Nevada, USA, decided that the 70-year-old former football, TV and movie star can be released in October.