The use of police cautions to deliver instant justice is to be reviewed because of mounting concern that they allow violent offenders to avoid court.

Jack Straw, the Justice Secretary, announced the move yesterday, only hours after the Director of Public Prosecutions called in The Times for an investigation of the way that out-of-court penalties operate.

Keir Starmer, QC, the director, and Sir Hugh Orde, president of the Association of Chief Police Officers, both expressed concern at the way cautions and fixed-penalty notices were working.

Half of all criminal cases in England and Wales are punished out of court. Up to 40,000 cases of assault were dealt with by a caution last year despite guidelines that say they should not normally be used for violent or sexual offences.

Mr Straw said that he and Alan Johnson, the Home Secretary, were concerned at the wide variation in rates of use of “out-of-court” penalties by police forces around the country.

He said the review would be conducted by the Office for Criminal Justice Reform and would involve HM Inspectorate of Constabulary and the Crown Prosecution Service.

Mr Straw told BBC Radio 4’s The World at One programme: “The guidance about cautioning is actually very clear. It says a simple caution should be used for low-level offending. Only in exceptional circumstances should it be used to deal with more serious offences. I understand the concerns that have been raised . . . but the guidance is actually very clear. What we are going to look at is how that guidance is properly applied.”

Asked if the review would increase the threshold so that no violent offence more serious than common assault would be dealt with out of court, Mr Straw said: “That is basically the way the system is supposed to operate at the moment and we will certainly be looking very clearly at that.”

The Justice Secretary denied that the Government had encouraged the use of cautions and fixed-penalty notices to ease the pressure on overcrowded jails. “That is absolutely not the case,” he said. “We have raised the prison population dramatically. It is going up all the time and there are many more spaces available.” He said that in most cases the offences being dealt with by the penalties would not previously have led to any police action.

Sources at the Ministry of Justice said that Mr Straw had intended to announce the review on Saturday when he addressed the annual meeting of the Magistrates’ Association in Birmingham.

Mr Starmer said in The Times that while there was a proper place for trivial offences to be dealt with outside the courts, the system had developed in an “incoherent way” and needed to be looked at again. “There is now a case to be made for a review,” he said.

“My view is there should be a structured, tiered approach which specifies what case will be dealt with at what level — and will be transparent.”

John Thornhill, chairman of the Magistrates’ Association, said: “We are very pleased and relieved to hear that out-of-court disposals are to be reviewed at long last as we have been airing our deep concerns about the inconsistent and inappropriate use of these penalties for over a year.”

Dominic Grieve, the Shadow Justice Secretary, said: “We already know that far too many serious offenders are being let off with a glorified parking ticket. There is no need for yet another review to kick the issue into the long grass. We need the Government to take some action.”

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