Hard cases, they say, make bad laws. But they may make for improved enforcement. The sentencing yesterday of an electronically tagged 15-year-old charged with stabbing a man to death may be an extreme example: the youth had breached the terms of his tagging order several times in the previous month. But this is far from an isolated incident.

The number of curfews imposed by courts, and monitored by electronic tags, has more than doubled over the past six years. Some 10 per cent of the total probation budget is now involved with tagging. Yet research by the Inspector of Probation finds that 57 per cent of tagged criminals violate the terms of their curfews. And more than half of the incidents involve serious violations. Neither is the situation new: a previous report in 2008 highlighted very similar problems.

Many breaches occur because of delays in enforcing the tagging orders: the Probation Inspector uncovered confusion between the Probation Service and the private companies to which tagging has been outsourced. But there are problems, too, with the poor quality of the information received from the court by tag-fitters. What is most striking is that all those involved are anxious to shift responsibility elsewhere. Rather than being distracted by a meaningless blame game, the Government's focus must be to develop concrete measures to tighten up the system.

The Government is keen to increase the use of tagging. Rightly so. Punishment in the community is preferable not only on cost grounds, but also because it can improve rehabilitation rates. But the system will not achieve anything if it is misapplied. As things now stand, not only are tagging curfews not being maintained, the technology is also not being applied in a targeted way. It is also too often used in inappropriate situations, such as domestic violence.

At present, the gap between the potential of tagging and the reality on the ground is inexcusably wide. Ministers may want to extend the maximum confinement at home from 12 to 16 hours per day. Before they can do so, however, public confidence in community sentences will need to be increased. That means ensuring there is a robust enforcement regime.