Serious Fraud Office director Grant Liddell made a brave and correct decision to hand over evidence showing NZ First leader Winston Peters misled the privileges committee, says an Auckland Queen's Counsel.
Jim Farmer said criticism of Mr Liddell's judgment by Prime Minister Helen Clark and her deputy, Michael Cullen, was wrong and unwarranted.
Mr Liddell's evidence was uncovered in the SFO investigation and showed that Mr Peters had a $40,000 debt paid for him by the Spencer Trust, contradicting his version that he paid it himself.
Dr Farmer said Mr Liddell had a simple choice: whether it was responsible to "sit on" relevant information, or to hand it over.
"He is in charge of his own office and should do what he thinks right.
"He has obviously taken a responsible decision. It is very defensible on its merits and it doesn't warrant attack from politicians, particularly personal attacks in the form of saying he has poor judgment."
The criticism of Mr Liddell's judgment was particularly directed at how he did not consult Crown Law before handing over the evidence.
As Attorney-General, Dr Cullen is the minister responsible for both the SFO and Crown Law.
Dr Farmer said there was no formal requirement for Mr Liddell to consult Crown Law and he had "no idea" why Helen Clark and Dr Cullen were suggesting this.
"In carrying out the investigative duties, the SFO and the director are intended to be independent and operate without influence from anyone," he said.
"Running off to Crown Law or the Solicitor-General to get advice - or approval, if that's what Dr Cullen is suggesting - doesn't seem to be obvious or even right."
The SFO's evidence about the $40,000 was obtained when it used its special powers to seize the Spencer Trust's records in its separate inquiry into the Sir Robert Jones and Vela family donations.
The records showed the trust paid the $40,000 legal costs Mr Peters was ordered to pay National MP Bob Clarkson after the unsuccessful electoral petition following the last election.
In a letter to the privileges committee, Mr Liddell said he approached it after considering "my responsibility as head of a law enforcement agency where I have information that is relevant to possible breach of the laws of New Zealand".