Last-minute decisions to drop prosecutions are costing the court service £30 million a year, shock new figures have shown.
Criminals who change their plea to guilty long after the trial process has begun are wasting another £47 million of public money.
The figures are in a report from public spending watchdog Audit Scotland, which says day-to-day delays in the court system wasted £10 million last year.
It was also revealed that the justice system cost £857 million in 2009/10, with less than 10% going on services to reduce reoffending.
Auditor General for Scotland Robert Black said much of the spending could be avoided.
“Scotland’s criminal justice system is very complex, involving many different public, private and voluntary organisations,” he said. “It means it is difficult to manage the system as a whole.
“There is still a significant amount of inefficiency in the system which results in delays, repeated processes and unnecessary costs. Much of this can be avoided and money could be saved.
“All the different bodies need to continue to work together to further improve the processes for the benefit of everyone involved.”
According to the report, the average cost of criminal legal aid was £642 for a summary case and £3,194 for more serious proceedings. It costs an average £34,279 a year for every prison place, while preparing a social inquiry report before sentencing costs £359.
A probation order costs £1,398 and supervising a community service order costs £2,769.
Meanwhile, the cost of interpreters, translators and expert witnesses increased by 62% in the eight years to 2009/10. And 37% of cases had to repeat a stage because somebody failed to turn up or lawyers asked for a delay.
Tory justice spokesman John Lamont said the report showed money was being wasted by the courts.
“This report underlines yet again that much more could be done to streamline Scotland’s criminal justice system and much more has to be done to rehabilitate prisoners,” he said.
“So much crime is fuelled by drugs and that is why we must invest in meaningful programmes to get addicts clean.”
Labour’s justice spokeswoman Johann Lamont said: “We owe it to victims of crime and their families to make the right decisions early on, so people have absolute confidence in the justice system.
“Being the victim of a crime is a horrendous experience for anyone and it should be victims who are at the centre of the system.”
Justice Secretary Kenny MacAskill said recorded crime is down, knife crime is down and serious criminals are being punished through the longest prison sentences in a decade.
He added: “This report recognises that good progress has been made. While I welcome that, I am clear that our work continues to build a stronger and more efficient criminal justice system to deal with offenders and better support victims of crime.
“We have to go further to tackle the remaining inefficiencies within the system. I expect to deliver savings of up to £14 million next year and much greater savings and performance improvements will follow.
“This will help justice organisations live within tighter budgets and provide better value for public money.
“It will also pave the way for a more strategic approach in areas such as IT co-ordination and performance information, building a criminal justice system fit for the 21st century,” the justice secretrary added.