The damage caused by the Government's planned sentencing reforms could be "irreparable", Labour has said.
Justice Secretary Kenneth Clarke is expected to outline his plans for a "rehabilitation revolution" in the justice system, including the extent of any U-turn over plans to halve sentences for offenders who plead guilty early.
But shadow justice secretary Sadiq Khan warned the plans will fail to "protect the public, punish and reform offenders, support victims and ultimately cut crime". He said: "I fear it will fail on every count."
Prime Minister David Cameron was lambasted in the Commons earlier this month for overseeing a "total mess" on sentencing after another apparent climbdown on a key policy.
Labour leader Ed Miliband said the Prime Minister seemed to have "torn up" controversial plans for halving jail time for serious criminals in the face of a major backlash.
The Premier backed Mr Clarke, who personally championed the sentencing reforms, saying he was doing a "superb job". But Mr Cameron is also believed to have ordered Mr Clarke to think again at a one-on-one meeting to discuss the plans.
The U-turn was greeted with delight by the Tory right - but it will leave Mr Clarke having to find up to £130 million of savings elsewhere at his department.
Under the sentencing plans outlined in December, judges would be given more discretion over how long killers should spend behind bars.
A "simpler, more sensible" approach that "leaves the judge to do justice in the individual case" will be put in place," Mr Clarke said.
Other measures included letting foreign nationals escape jail as long as they leave the UK forever, wiping the slate clean for young offenders when they reach 18 so they are not hindered by a criminal record, and halving sentences for those who plead guilty early.