More than 30 families have called on the government to stop killers convicted of any form of manslaughter being released early to ease prison overcrowding in England and Wales.
In a letter to Justice Secretary Alex Norris, the families said they felt victims were "being asked to bear the consequences of the prison capacity crisis".
Signatories include Emma Webber, whose son Barnaby was stabbed to death in the Nottingham attacks in 2023, and whose killer Valdo Calocane was convicted of manslaughter on the basis of diminished responsibility.
Speaking on Radio 4's Today programme, Bridget Phillipson, Minister for Women and Equalities, defended the early release scheme.
She said the government had faced "some really difficult and unpalatable choices" in dealing with prison overcrowding and that they had faced "the wholesale collapse of the criminal justice system".
The scheme, external aims to ease prison overcrowding in England and Wales.
The families of those affected by homicide have called for those convicted of any form of manslaughter to be excluded.
Those convicted of murder and those serving sentences for rape, serious child sexual abuse and grooming offences are already excluded from the early release scheme.
Calocane fatally stabbed students Barnaby Webber and Grace O'Malley-Kumar, both 19, and school caretaker Ian Coates, 65, on the streets of Nottingham on the morning of 13 June.
He then stole Coates's van and used it to drive into three other people, seriously injuring them.
Calocane admitted three counts of manslaughter and three counts of attempted murder on the basis of diminished responsibility, and was sentenced to an indefinite hospital order in January 2024.
The letter comes after Prime Minister Andy Burnham indicated the government would make changes to the early release scheme to ensure that the killers of PC Andrew Harper, who were convicted of unlawful act manslaughter, are not eligible.
The letter also highlighted concerns that some of the most serious domestic homicides result in convictions of voluntary manslaughter and that it would be "difficult to reconcile with the government's commitment to halve violence against women and girls" if those offenders were released early.
The families said they had "deep concerns about how early release may apply in homicide".
They wrote: "As the government considers excluding unlawful act manslaughter from the scheme, it must follow that all forms of manslaughter are also excluded.
"We have spoken with numerous bereaved families affected by homicide.
"A consistent theme has emerged: many feel that victims are being asked to bear the consequences of the prison capacity crisis through the earlier release of those convicted of the most serious offences.
"Whether intended or not, this is creating a growing sense that justice for victims and public protection are being compromised in order to address pressures elsewhere in the system.
"We therefore urge the government, as it seeks to prevent those responsible for the killing of PC Harper from benefiting from the early release scheme, to ensure that voluntary manslaughter is also brought within the proposed exemption."
Other signatories include:
John Hunt, whose wife Carol and their daughters Hannah and Louise were killed in their home by Louise's ex-boyfriend Kyle Clifford in 2024. Clifford was convicted of three counts of murder and sentenced to a whole-life order.
Diana Parkes, whose daughter Joanna Simpson was killed by her estranged husband Robert Brown in 2010. Brown was convicted of manslaughter on the basis of diminished responsibility.
John and Penny Clough, the parents of Jane Clough, a nurse who was murdered in 2010.
Josh Rook, whose sister Annabel Rook was murdered by her partner Clifton George in 2025.
Phillipson said: "We have been clear that the most serious offenders will be exempt from that early release programme.
"But the reality of what we are confronting is that, if allowed to go unchecked, we could end up in a position where someone who is arrested for very serious offences, for example offences related to violence against a woman, and we wouldn't have anywhere to send that individual."
A Ministry of Justice spokesperson said: "We share the public's anger that these options are even being considered, after we inherited a prison system on the brink of collapse.
"We are fixing this by building 14,000 new prison places, expanding electronic tagging on an unprecedented scale, and investing in probation services at record levels.
"We are also exploring how we can go further, including faster deportation of foreign criminals, better use of the women's estate and reviewing the unjust IPP sentences."
The prime minister has asked the justice secretary to present a plan for further changes of the early release scheme to parliament next month.
Phillipson confirmed that "full details" would be set out before parliament next week.
