Justice secretary Ken Clarke's Breaking the Cycle green paper was widely welcomed by prison reformers last week as a watershed that could bring to an end the 18-year punitive arms race that has fuelled the relentless rise in the prison population.
The moderate package holds out the promise of an intelligent sentencing framework and a "rehabilitation revolution" that would cut the high reoffending rates of more than 60%. The prize is a 3,000 cut in the record 85,000 jail population in England and Wales within four years, while continuing to drive down crime.
But will it work? The green paper has had a difficult birth. Its publication was delayed because of "presentation concerns" within Downing Street and within hours of its publication it was branded a "criminal's charter" by the Tory tabloids.
The unfounded claim that Clarke was intent on giving murderers shorter sentences spooked Downing Street as the Sun threatened a prolonged campaign demonising Clarke as a "hand-wringing social worker" and a "softie justice minister". It was the day that the Tory backbenchers and tabloids discovered they were in coalition, not just with the Liberal Democrats but also with Clarke.
The justice secretary, a fully paid-up member of the campaign for real politicians, can look after himself. But the skirmish was an early reminder that if the package is to have any chance of success, it will require as vigorous a political campaign by coalition ministers as was first mounted by Michael Howard when he ushered in his "prison works" orthodoxy nearly two decades ago.
It matters because for all the excellent initiatives in the green paper, from diverting mentally ill people from prison to doing something about the 3,000 inmates who are held beyond their tariff with no prospect of a release date, the package has yet to win a place in the coalition's legislative programme. Clarke says a bill will follow the green paper next May, but presumably that will be a draft bill. Ministers say they would "ideally" like to see it in next autumn's Queen's speech but they don't appear to be on a promise.
Assuming the package makes it over that hurdle, can it work in criminological terms? At first sight it appears a rather disparate package of about a dozen different measures. In the short term, proposals such as increasing the average sentence discount for a guilty plea from 25% to 34% would have the biggest impact, saving 3,400 prison places a year by 2014/15 and £130m. In the medium to long term, scaling up the use of social impact bonds to finance payment by results intervention programmes could unlock potentially £100m of ethical investment from charitable trusts.
All the disparate measures add up to an attempt to halt what criminologist Rod Morgan has called "sentence inflation" that has raged unchecked since the early 1990s. So at the bottom of the sentencing menu, there is a concerted attempt to reinvent the fine, with the use of compensation orders, reparations to victims and seizing cars and other assets instead of lower-end community penalties. Community payback itself is to be made more effective, especially unpaid work schemes, through the use of providers other than probation.
Can it be done at a time of major spending cuts? A leaked justice ministry letter earlier this year shows that 5,780 jobs could go in prisons and probation as a result of the reforms. The probation service caseload is already as overcrowded as the prisons, so offender interventions provided by the private and third sectors will have to be on top of existing provision if these reforms are to work.
Ultimately, it will be easier for Clarke to get his plans for 40-hour working weeks in prison and tougher community penalties through the Commons, but he may have to rely on Labour votes to get his more lenient sentencing regime on to the statute books. Let's hope Ed Miliband stands by his acknowledgment that "Ken is right on prisons".