In US Forensic Expert: UK Defendant Convicted with NSA Email Sweep (Part 2), internet security expert witness writes:
Nonetheless, 83 pages of email drafts covering about 29 weeks were produced as evidence. SOCA (Serious Organized Crime Agency) Senior Investigating Officer, Paul Ashton, told the jury in the drug conspiracy trial that a letter of request (LOR) for assistance was sent to the FBI, which in turn provided the Yahoo! data that the jury was reviewing. Although the email evidence was discussed in open court, multiple reports by BBC News never mention email.
Speaking from the California laboratory of Burgess Forensics, the analyst said, "With Snowden's releases in the Washington Post and Guardian and the NSA's subsequent acknowledgement of the formerly secret PRISM program, we now know a means for that Yahoo! data to have surfaced, and at this point PRISM is the only possible known route for it to have come to light."
UK Foreign Secretary, William Hague addressed the UK House of Commons on June 10, 2013 and stated that "It has been suggested GCHQ [The UK’s Government Communications Headquarters] uses our partnership with the United States to get around UK law, obtaining information that they cannot legally obtain in the UK. I wish to be absolutely clear that this accusation is baseless."
However, counsel for the defendant states that “the email data produced at trial was not produced as stated by the prosecution, based on expert reports. As the experts state the email data has been produced by interception of the email account, and PRISM is the only explanation - such obtained evidence would be inadmissible in a UK courtroom.”
Responses to the legal team’s requests of Yahoo!, law enforcement agencies in the both the UK and the US have continued to hold a pall of secrecy over official explanations as to how the email evidence was obtained. Nevertheless, the defendants in the case have been given more than 80 years’ imprisonment on the basis of such evidence.
Counsel has sent a letter directly to the Yahoo! Board of Directors in Sunnyvale in an attempt to receive an explanation as to how Yahoo! obtained the email data, which they themselves said could not be obtained.
Appeals are ongoing.