After 11 weeks of legal argument, Judge Harvey Crush said the prosecution's failure to make proper disclosure to defence lawyers meant there had been an abuse of process and the defendants could not get a fair trial.
Abandoning the trial of a Scotland Yard officer and seven other defendants accused of conspiracy to import £12 million worth of cannabis resin into the UK, Crush attacked the "culture of non-disclosure and non-compliance" which, he said, is rife in the prosecution.
Sitting at Maidstone Crown Court, the judge found that the prosecution had adopted a "cavalier attitude" to providing the defence with evidence.
The 1996 Criminal Procedure and Investigation Act, requires the CPS to certify that it has provided defence lawyers with all the material that might undermine the Crown's case.
In this case, this was done in March last year, but after the had trial started the Crown revealed it had hundreds of pages of new evidence on a supergrass, Richard Price, who had admitted his part in the conspiracy and was to have been called to give evidence.
Crush said the failure to record some evidence breached both the police and court codes of practice.
The cost of the police investigation and trial comes to around £5 million, a figure set to increase if, as expected the defendants make claims for damages.
The CPS says it is to carry out a thorough review of the case