When a hospital doctor picks up a patient's file, he needs to see the patient's medical history; what treatment is being given and what drugs have been prescribed. If the file is incomplete and can't be relied on, the system would collapse.

The same is true with court files. But in a damning report published today, the Inspectorate of the Crown Prosecution Service found that most files - both in the magistrates' courts and in the crown court - are incomplete.

And it is not just minor details that are missing. In an alarming 36 per cent of cases, the file did not record the defendant's bail status. In 11 per cent of magistrates' court files and 18 per cent of crown court files, the outcome or decision of a hearing was not recorded. And in 16 per cent of magistrates' courts and 35 per cent of crown court files, the need for follow-up work was not recorded - or highlighted as necessary.

This, as Stephen Wooler, the Chief Inspector of the CPS pointed out, is not just a matter of good housekeeping. The result of such shoddy work is delay; duplication of work by other people and inefficiency throughout the court system.

Worse, it can mean cases being lost (and offenders escaping being brought to justice) one incident uncovered by the audit found that new evidence had been lost: "it was amongst loose papers inside a file and there was no endorsement to show that it had been seen by a lawyer before a decision to drop the case was taken." The report adds: "in one case....poor housekeeping led to a case being dropped after protracted problems in using CCTV evidence."

There are other adverse consequences. Incomplete files can lead to poor communications with victims and failures to monitor custody time limits: that in turn, the inspectors say, to defendants being detained unlawfully or - conversely, being released from custody simply because the CPS has not applied for an extension to the time limit.

This report into day-to-day failings in the nuts-and-bolts work of prosecutors comes at a time when the reputation of the CPS nationally is good. The Director of Public Prosecutions, Sir Ken Macdonald, who this week announced he was retiring from the post in October, is credited with turning the CPS around. Once widely derided, the butt of jokes about all things wrong with the criminal justice system, he has overseen the strengthening of its role, particularly the taking on of charging offenders, from police.

The service has become a popular employer and attracts large numbers of applicants. Above all, he has underlined its independence, taking a tough stand, for instance, over the decision on whether to prosecute over "cash for honours".

But its reputation ultimately comes down to the quality of prosecution work in the courts. With plans to expand the role of prosecutors into the crown courts, the CPS cannot afford to be found wanting in such routine responsibilities as ensuring case files are complete. The old joke about the CPS was that it had lost the file; now it will be that the file cannot be relied on.

The CPS says it has taken action to improve matters and a new case file system is being brought in that will help. That action needs to be swift and thorough - to ensure that overall progress of the past four years is not undermined by continuing failings on the ground.

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