BBC Radio 4's Law in Action
From teaching criminals gardening to making violent offenders apologise to their victims, it seems almost everything has been tried to make criminals go straight.
How do you break a cycle of revolving prison doors?
Preventing criminals reoffending is hard. Around two-thirds of prisoners continue to go back to crime within two years of being released and the figure remains stubbornly high despite several measures to improve the situation.
There are some cutting-edge techniques being tried out but in an investigation for Radio 4's Law in Action programme, I found a worrying lack of research evidence into what actually works to stop people ending up back in prison again.
I met Quince Garcia - a former crack dealer. He went through a rehabilitation programme called Time for Families. It organises extended family visits to the prison lasting several hours and including a meal.
The technique works on what is called "social capital" - the prisoner's stock of connections to law-abiding friends and family members.
The aim is that once out of prison, offenders do not simply go back to the same criminal social circles and end up back out committing crime.
Quince's sister, Quinita, noticed the change in her brother after the parenting classes.
"He'd become a lot more humble, very humble, in touch with himself more. He is still stubborn but he was much more stubborn before that."
Quince said it gave him strength within and has been going straight for nine months since his release.
"I decided to change before these programmes but these programmes guided me. You've got to want to change."
But it remains unclear whether rehabilitation programmes can take the credit for changing Quince - or if Quince simply chose to change himself.
I discovered a serious body of opinion in the Home Office that is trying to find out definitively what reduces re-offending. It is known as the "what works" movement.
It believes prison schemes should be evaluated the same way medicines are tested by the NHS.
Costly to run
The idea is that groups of prisoners who go on rehabilitation schemes should be compared with a control group selected at random who do not get the special treatment. These "randomised control trials" are the same way drugs are tested.
The problem is that the trials are so expensive and require so many participants that, in effect, only the Home Office can run them. And critics say there has not been enough investment in this kind of research yet.
What results there have been so far have emphasised things like dealing with drug and alcohol addictions, improving prisoners' chances of getting a job and finding accommodation.
The government can point to several policies that recognise the importance of rehabilitation - for example, a new agency called the National Offender Management Service (NOMS) - to manage offenders between prison and the community.
Critics say this initiative failed to deliver the promised reduction in re-offending after David Blunkett's departure from the Home Office.
Martin Narey, former head of the prison service, was the first head of NOMS and he said that it could by now have been providing a "much more effective criminal justice system".
"If you have home secretaries who are not much interested in the priorities of the predecessor, but want to set their own agenda, then the chance of bringing any strategic management to the Home Office is going to be thwarted."
Another fundamental problem with initiatives like this, aimed at cutting re-offending, is that it is often unclear which schemes work across the board because the research has not been done.
It is certainly not true that this government has been soft on crime. A combination of new laws and a harsher public climate on law and order mean the prison population - currently approaching 90,000 - is the highest in British history. Sentences are getting tougher. Crime has fallen.
With so many people locked up, it is all the more striking that prison is not reducing the likelihood of people offending again.
Law in Action can be heard on Tuesdays at 1600GMT on Radio 4 or afterwards at the programme website.