Claims Crown's lawyers failed to disclose evidence in several cases, including the Mark Kennedy environmental activism affair.
Sir Christopher Rose, who retired as a judge in 2006, has been appointed to lead an inquiry into claims the CPS suppressed evidence. Photograph: UPPA
The Crown Prosecution Service faces a crisis following the abandonment of a series of trials after allegations of serious wrongdoing were made against its staff.
Senior officials at the CPS stand accused of repeatedly failing to meet their legal obligation to disclose crucial evidence and ensure fair trials.
Sir Christopher Rose, a former appeal court judge, has been appointed to lead an inquiry into claims the CPS suppressed evidence relating to the undercover police officer Mark Kennedy.
His inquiry will test whether prosecutors in the Kennedy case met the fundamental obligation of disclosure, to give lawyers for the accused any evidence that could assist their defence.
The Guardian can reveal that the same CPS lawyer in the east Midlands allegedly implicated in the Kennedy case has been accused of non-disclosure in two other trials.
The cases – one concerning fraud, the other drugs – were abandoned in recent months after prosecutors were alleged to have withheld evidence.
The development threatens to widen the controversy stemming from the Kennedy affair, which until now has focused on prosecutions of environmental campaigners.
On Tuesday, 20 activists convicted of planning to break into the Ratcliffe-on-Soar power station will challenge the guilty verdicts at the court of appeal. If successful, their case will be considered a shocking miscarriage of justice.
Failure to disclose surveillance tapes led in January to the abandonment of a trial of six other activists, who were accused of conspiring to break into the same power station.
The Ratcliffe case and the fraud and drugs trials involved the same senior CPS lawyer, Ian Cunningham.
His name first came to light on 6 January, when the fraud trial at Nottingham crown court collapsed after it emerged that three defendants – Mark Taylor, Robert Sankey and Neil Lievesley – had been wrongly accused of fraud by a business partner.
The three businessmen were connected to Aussie Mole, a company making pneumatic hammers for laying pipes and cables.
The CPS told the judge it had dropped the case, after it realised evidence in its possession suggested the men's business partner – the key witness – was not, as the judge put it, "a witness of truth".
Judge Andrew Hamilton demanded to know why the prosecution, costing up to £20,000 in public funds, had been mounted.
"This is entirely wasted money," he said. "Who has been responsible for wasting this money?"
He added: "These three men have been in fear of being locked up. They've no doubt spent a pretty rotten year or more worrying about what's going to happen to them and it's all for no purpose."
Demanding a written explanation, the judge said he wanted to know why Cunningham had initially withheld the crucial evidence – a statement from a principal witness in the case – from defence lawyers.
"It's indefensible ... this is not a police constable who doesn't know what's what. Mr Cunningham is a senior crown prosecuting solicitor. I just cannot fathom how he could have made such a decision."
On Monday, a CPS statement confirmed that an explanatory letter was sent to the judge on 16 February.
The CPS said a key witness statement had been originally marked as being not for disclosure to the defendants. It was given to them seven months before the case was dropped, the CPS added.
"Disclosure was carried out, albeit late, and a full explanation was given to the judge, which he has raised no further questions on," the statement said.
"While it is clear some aspects of the case could have been handled better, this case was not dropped due to the disclosure issues."
But the case raises serious concerns. Every criminal investigation generates masses of documents. Police and the CPS select those documents which they believe will help secure a conviction.
It is a cornerstone of the justice system that prosecutors must also disclose to the lawyers working for the defendants any relevant document that would help their defence.
The fraud allegations were first made against the three in 2007, but CPS officials in Derbyshire decided not to prosecute.
The file was later passed to the complex case unit of the CPS, which deals with "particularly sensitive and high profile" cases. Cunningham decided to revive the prosecution as he believed the witness was credible.
It was Cunningham's name that was at the centre of controversy that erupted four days later in the same Nottinghamshire courthouse.
The Kennedy case hit the headlines on 10 January, when the CPS announced it would abandon its prosecution of six climate change campaigners accused of planning to break into the Nottinghamshire power station.
Prosecutors acted after it emerged that a transcript of Kennedy's surveillance of the activists had not been disclosed to the defence.
It was not until last month that the Guardian revealed police allegations that Cunningham had withheld the material from defence lawyers, leading the director of public prosecutions, Keir Starmer QC, to announce an independent inquiry.
That development had a domino effect on the third abandoned trial in which the CPS has been accused of suppressing evidence. Details of that trial cannot be reported for legal reasons, but it involved accusations of conspiring to supply drugs.
Before the prosecution opened its case, defence lawyers lodged an "abuse of process" application, calling for the charges to be cast aside.
The complaints involved concerns that the defendants would not get a fair trial because police and prosecutors, including Cunningham, had failed to disclose important evidence.
Defence lawyers wanted to know why Cunningham, one of two CPS officials running the prosecution, had decided not to disclose the evidence – questioning whether he had been misled, behaved dishonestly or simply not looked at the documents.
The dispute resulted in Cunningham having to attend court where, under cross-examination, he told a judge he had not handed material to the defence because he wanted to give himself more time to consider the question.
In his ruling, the judge found there were some failings in the disclosure process, but he rejected the application – essentially ruling in favour of Cunningham and the police.
That decision was overtaken when lawyers for the defendants arrived in court with copies of the Guardian, which contained details of allegations against Cunningham in the Kennedy case.
The judge first adjourned the hearing while he read the articles and then cancelled the trial. A new jury will be sworn in, after the Rose inquiry has determined whether Cunningham was at fault in the Kennedy case.
A CPS spokesman said: "There have been no findings against Ian Cunningham at this stage. We await the outcome of the independent inquiry into the Ratcliffe-on-Soar case."