Police and prosecutors are wasting £55m a year by mishandling court cases, a report by a Commons watchdog has said.
Delays are an "affront" to the expectation of swift justice, say MPs
The Public Accounts Committee said more than 900,000 out of about 3m magistrate hearings did not go ahead as planned in England and Wales in 2004-5.
The delays cost an estimated £173m - of this the police and Crown Prosecution Service (CPS) were responsible for £24m each, plus £7m jointly, say the MPs.
However, the CPS said the number of ineffective trials was falling.
'Waste of money'
Prosecution errors leading to delays included losing files or not producing evidence in time.
Mr Leigh said: "The CPS and the police are jointly responsible for an alarming number of delayed and ineffective trials in magistrates' courts.
"This is not only a waste of taxpayers' money - some £55m a year - but also an affront to society's expectation and demand that the guilty be swiftly brought to justice."
He said the CPS had to "sharpen up its performance" and start to "emulate the most successful private law firms".
Liberal Democrat legal affairs spokesman Simon Hughes said the police and CPS had been caught "bang to rights".
"They are both in the dock for good reason - and both are guilty," he said.
Committee member Richard Bacon urged judges to get tough on criminals who enter a last-minute guilty plea.
The report suggests guilty pleas were entered on the first day of 40,000 trials in 2004-5, or 21% of the total number.
"Criminals should not be rewarded for pleading guilty at the last minute with over-generous reductions in their sentences," said Mr Bacon.
The Director of Public Prosecutions, Ken Macdonald QC - who heads the CPS - has admitted the organisation does have an "old-fashioned culture".
But he said reforms to reduce the number of ineffective trials and hearings were beginning to work.
The CPS said figures showed that between June and August this year, the proportion of mishandled cases was 19%, which is a fall of 4% from last year.
It also noted that nearly a third more offences were brought to justice last year than in 2001-2.
The CPS is planning to implement a new business model as well as more policies to help police "get the charges right first time", support prosecution witnesses and ensure better trial management, a spokeswoman added.