Allowing a senior policewoman to publicly give evidence about corruption allegations at News International was a "spectacular failure", Rebekah Brooks's lawyer has said.
Stephen Parkinson said evidence given by Sue Akers at the Leveson Inquiry had brought "much prejudicial material" into the public domain - which could result in an unfair trial if any charges are brought.
The Scotland Yard Deputy Assistant Commissioner, who is leading the investigation into illegal newsgathering, told the inquiry into press standards that there was a "culture of illegal payments" at the Sun newspaper.
Akers, who is in charge of three linked inquiries into phone hacking, illicit payments and computer hacking, told Lord Justice Leveson the payments appeared to have been authorised at a "senior level".
This week it was announced that the Attorney General is looking into concerns the policewoman could have prejudiced any potential trials.
Writing in the Daily Telegraph, Parkinson said: "There is no excuse for the spectacular failure that occurred last week.
"Normally our system protects those who are suspects in criminal investigations reasonably well ... it restricts the circulation of facts, comment and speculation about their guilt or innocence.
"Last week, that did not happen - and it has not happened for much of the last seven months.
"Witnesses have been summoned before both parliamentary committees and the Leveson Inquiry. As a result, much prejudicial material has come into the public domain."
The attorney general Dominic Grieve is looking into claims Akers' evidence could prejudice any trial.
Brooks, a former editor of The Sun and a former chief executive of News International, remains on bail after being questioned by detectives last summer on suspicion of phone hacking and corruption.
She was arrested and questioned in July, days after resigning as chief executive.