MPs have criticised the director of public prosecutions over failings in the disclosure of evidence in rape and serious sexual assault cases.
A number of rape trials collapsed last year after it emerged vital evidence had not been given to defence lawyers.
A new report from the Justice Select Committee said Alison Saunders did not recognise the severity of the issue and there was “insufficient leadership”.
Ms Saunders said addressing problems in the system was her “top priority”.
She is due to stand down from her post in October at the end of a five-year contract.
In the lead-up to criminal trials, police and prosecutors have a duty to disclose evidence or information that might either help the defence case, or harm the prosecution’s case.
But in January, the Crown Prosecution Service (CPS) ordered a review of more than 3,600 cases in England and Wales after four cases were thrown out of court due to a lack of disclosure.
The trial of Liam Allan was stopped in December at Croydon Crown Court, days before the prosecution of Isaac Itiary at Inner London Crown Court was halted.
And in January, the case against Samson Makele was stopped at Snaresbrook Crown Court in east London, while Oxford student Oliver Mears – who had spent two years on bail – had the case against him dropped days before his trial was set to start.
The review found that 47 cases of rape and sexual assault had important evidence withheld from the defence.
Committee chairman, Conservative MP Bob Neill, said the police and CPS often see the disclosure of evidence as an “administrative headache” – a view which was “not acceptable”.
Mr Neill, a former barrister, added: “Disclosure failings are extremely damaging for those concerned and can have a permanent life-long impact.
“These failings have caused miscarriages of justice and – as the director of public prosecutions even admitted to us – some people have gone to prison as a result.”
The committee found failings in the “application of disclosure by police officers and prosecutors on the ground” and called for a culture change, so it was seen as a “core justice duty”, rather than an “administrative add-on”.
When it came to Ms Saunders, they said there was “insufficient focus and leadership” in dealing with the problem and that she “did not sufficiently recognise the extent and seriousness” of failures within the process.
The report, published on Friday, also called on the government to look at whether there is sufficient funding for the system.
Mr Neill said: “The proliferation of electronic evidence makes disclosure ever more challenging, and we need the right skills, technology, resources and guidelines, to resolve this once and for all.
“The failings are symptomatic of a system under immense strain: without change, we cannot expect the public to have confidence in the criminal justice system.”
Responding to the report, Ms Saunders said: “I have been very clear that addressing the long-standing problems in managing disclosure across the criminal justice system is my top priority.
“There is an unprecedented focus on finding solutions, and extensive action has been under way over the past year to bring about the necessary change not just in how cases are handled, but in the wider culture within the CPS and policing.
“This is not a quick fix. We will evaluate the measures taken, and agree further commitments to ensure there is continuous improvement.”
The National Police Chiefs’ Council’s lead for criminal justice, Chief Constable Nick Ephgrave, defended Ms Saunders, saying she was “fully aware of the extent and seriousness of the disclosure failures” and “fully committed” to working with them.
Another review into disclosure is being carried out by the attorney general and a National Disclosure Improvement Plan is being put into place.