The number of prosecutions in England and Wales that collapsed because of a failure by police or prosecutors to disclose evidence increased by 70% in the last two years, the BBC can reveal.
Last year, 916 people had charges dropped over a failure to disclose evidence – up from 537 in 2014-15.
It comes after recent collapsed rape cases highlighted a failure to share evidence with defence solicitors.
The Crown Prosecution Service said the justice system had “systemic” problems.
In the lead up to criminal trials, police and prosecutors have a duty to disclose evidence that might either assist the defence case or undermine the prosecution’s.
However, the recent collapse of several rape cases has heightened concerns that evidence is not being disclosed early enough, and that the rules are not being followed.
‘A daily struggle’
In December, the trial of Isaac Itiary, who was accused of raping a child, collapsed when new evidence came to light.
During Mr Itiary’s trial, police failed to disclose messages which showed the girl, then 16 years old, had told the defendant she was 19.
The same month, the trial of Liam Allan, who faced 12 counts of rape and sexual assault, was also halted.
The case against Mr Allan was dropped when it emerged evidence on a computer disc – which police had looked through – showed messages from the alleged victim pestering him for “casual sex”.
The new figures, obtained by BBC News under the Freedom of Information Act, have revealed the total number of collapsed cases over the past four years.
In 2013-14, 583 people had their trials ended or the charges against them dropped due to a failure to disclose evidence.
That figure fell to 537 in 2014-15, before it increased to 732 the following year, and 916 last year.
During the same time the number of completed prosecutions fell by almost 150,000 cases – from more than 736,000 in 2013-14 to just over 588,000 in 2016-17.
‘Still too many’
Angela Rafferty QC, chair of the Criminal Bar Association, blamed issues on a “lack of investment, training and attention to the criminal justice system”.
She said barristers face “a daily struggle in respect of disclosure, delays and all the other disastrous consequences of a system that is openly described by MPs as at breaking point”.
“The reasons for it must be properly explored and dealt with,” she added.
She said Richard Foster, chairman of the Criminal Cases Review Commission, had written to the director of public prosecutions and the attorney general 18 months ago about the problem.
A CPS spokesperson said the number of dropped cases due to evidence disclosure failures represented just 0.15% of the total number of prosecutions.
“That is still too many, however, and we are clear that there are systemic disclosure issues across the criminal justice system which will require a collective effort in order to bring about improvement.
“Getting this right is a priority, and along with the police and other criminal justice partners we are working to improve how we fulfil these vital disclosure obligations.”