Nearly a quarter of all prisoners in the UK should be released on parole to ease overcrowding, a judge has said.
Judge Compston said prisons were currently unable to work properly
Judge Compston of the Thames Valley circuit told a research group that the radical plan was the only way to enable overcrowded jails to work properly.
He also called for discipline in schools to be "robustly reinforced".
The head of the Rethinking Crime and Punishment research group, Rob Allen, said it was very unusual for judges to comment on matters of policy.
The judge, who sit at crown courts including Oxford and Reading, said: "I would rethink crime and punishment by within six months releasing at least 20,000 prisoners from prison on parole.
"The prisons are grossly overcrowded and cannot do their job properly.
"We also need to robustly reinforce justice in schools, starting with nursery schools.
"Unless this is tackled now, the next generation will reap a whirlwind."
He added: "We also need to stop politicians meddling too much and too often, to educate the media who are often unfair and provocative, to mentor selected offenders under judicial supervision and to send less people to prison."
Mr Allen said Judge Compston had responded to an invitation issued by the group for comments on possible law and order reforms.
"It's quite difficult to get judges to say anything about these sorts of matters, apart from the Lord Chief Justice," said Mr Allen.
"I think there is a lot in what he has to say, although I'm not sure whether the 20,000 figure has been rigorously calculated.
"He is probably referring to those inmates serving short prison sentences - which tend to achieve little - and mainly to non-violent offenders."