Criminals are getting away with failing to turn up for unpaid work imposed as part of their sentence, a new report reveals.
Watchdogs found some offenders' absences from assignments were wrongly deemed acceptable.
In a sample of cases which should have resulted in fresh action against those who repeatedly missed sessions, inspectors found only a third were brought to book.
The inquiry by HM Inspectorate of Probation uncovered examples where fewer than one in four offenders scheduled to attend showed up for work.
In one example cited in the report, an offender had completed just 16 hours of unpaid work in 17 months since being sentenced, while another had more than 50 "unacceptable" absences.
Chief Inspector Paul Wilson said: "Although we found some high quality management and delivery, much of it was simply not good enough, lacking in focus on the basic requirement to deliver and enforce the sentence of the court."
Unpaid work is the most frequently imposed requirement of a community sentence, with more than 70,000 orders made in 2014.
Inspectors examined arrangements for 100 offenders required to attend work placements and projects as part of their punishment.
In most areas the number of individuals scheduled to attend considerably exceeded the number that could be put to work, with projects operating on the basis that two-thirds of offenders would show up, the report said.
It added: "In some areas the ratio appeared to be very different. We saw several examples where fewer than 25% of those scheduled had attended."
In cases where an offender does not attend as instructed, an entry is made on their computerised record and alerts their offender manager.
At this point the manager should instigate an inquiry to determine if the absence is either acceptable or unacceptable.
But the report said: "We found several cases with high numbers of failures to attend that had not been defined as either acceptable or unacceptable."
In 77 cases which required the offender manager to make a judgement about absences, 29 were "broadly correct", but inspectors thought decisions were not correct in 21. There was insufficient information to take a clear view in the remaining 27.
"In too many cases, there was insufficient evidence to justify the decision that an absence was acceptable. In other cases, a judgement had simply not been made, the judgement was incorrect or no action had been taken," the report said.
There was at least one unacceptable absence recorded in 53, or more than half, of the cases inspected, including eight with six or more unacceptable absences.
Criminals should be given a warning for a first unacceptable absence and then face enforcement action for a second.
In 28 cases there was a "strong case" that enforcement proceedings should have been launched, but this happened in only nine, the report said.
In early one in five of the sample cases, the offender's work appointment had not been arranged in the first three weeks after sentence, which was described as "unacceptably high".
A Ministry of Justice spokesman said: "It's totally unacceptable for offenders to skip work enforced by the courts.
"We want much more effective rehabilitation - and that's got to start with making sure offenders turn up on time and face consequences if they don't.
"We accept all the recommendations for the Ministry of Justice in this report and are already taking action to implement them.
"We have also made sure Community Rehabilitation Companies produce action plans to address concerns and are closely monitoring their progress."