The most senior judge in England and Wales is urging ministers to pass new criminal laws only if they are "absolutely necessary".
Lord Woolf says reoffending rates may shock people
Lord Woolf used a speech to argue the criminal justice system needs time to absorb previous changes and deliver an effective service.
He was speaking ahead of next week's Queen's speech, which will map out the government's legislation plans.
Lord Woolf also raised concern on the failure of prisons to stop reoffending.
But he argued public perceptions about courts delivering lenient sentences were misplaced.
Reform roll out
The comments came as Lord Woolf, the lord chief justice, delivered the Leon Radzinowicz lecture at Cambridge University.
His concerns about continued justice reforms come after it emerged in February that Tony Blair's government has created 1,018 new criminal offences since 1997.
The prison and probation services are currently being merged into the National Offender Management Service.
Crown and magistrates' courts have also been reorganised and a new Supreme Court is set to replace the House of Lords as the highest court of appeal.
In his lecture, Lord Woolf said there was a need to "bridge the gap" between how the public viewed sentencing and the reality.
"Fourteen years ago the prison population was 42,000 and falling, while today it is 76,000 and forecast to rise," he said.
"This is apparently wholly contradictory to public perceptions who believe that courts are unduly lenient.
"What perhaps should come as a shock to the public is how unsuccessful we have been at preventing reoffending.
"The cost of reoffending by ex-prisoners is £11bn per year and the incidence of reoffending after the completion of a sentence is at an unacceptably high level."
Lord Woolf, who has championed penal reform since his report on the Strangeways prison riot in 1990, argued prison overcrowding made it harder to tackle reoffending.
"If an offender is returned to society at the end of his sentence with increased skills, a job to go to and accommodation, the risk of that offender reoffending is significantly reduced," he added.