Discounts on jail terms handed to criminals who plead guilty may be slashed thanks to recommendations due to be published.
The official panel which issues sentencing guidelines to judges has considered whether maximum reductions should be capped.
The draft recommendations from the Sentencing Guidelines Council are also expected to include limits on the time which can be deducted from a jail term when a criminal has been caught "red handed".
Home Secretary John Reid and Attorney General Lord Goldsmith expressed concern that existing discounts are contrary to the interests of justice.
Mr Reid expressed dismay that babysitter paedophile Alan Webster got a third off his sentence after police confronted him with sickening pictures, effectively giving him no choice but to enter a guilty plea.
Webster, 41, from Hatfield, Herts, raped a 12-week-old baby and took photographs of the abuse with his girlfriend Tanya French, 20.
The SGC report follows a study published last May by the Sentencing Advisory Panel.
It said: "Having a reduction based on a proportion of the sentence increases the benefit of the reduction in relationship to the severity of the sentence.
"This can result in a very substantial reduction where long custodial sentences or high fines are imposed."
It also questioned what level of discount should be allowed when a defendant has been caught red-handed and the prosecution case was "so overwhelming that the defendant had no grounds on which a not guilty plea could be entered".
Imo they should not be allowed to have time cut from there sentences even if they do plead guilty or are caught red handed, prision life is easy enough for them why make it any easier ?