Auckland lawyer Barry Hart has been found guilty of professional misconduct.

He faced three charges of misconduct and one charge of conduct unbecoming of a barrister, including that he overcharged fees, obstructed the Auckland District Law Society's investigations and did not pay the full amount to a private investigator he had hired.

In testimony to the Auckland Lawyers and Conveyancers Disciplinary Tribunal, standards committee lawyer Paul Collins said a case for which Hart charged $35,000 would have been done easily by another lawyer for $15,000.

A two-day hearing took place at Auckland District Court last month but Hart did not attend after sending a medical certificate which said he had chest pains, breathing difficulties and fatigue.

The tribunal said the certificate gave little detail of his diagnosis and stated he was not fit for work "in particular court work".

Hart, 70, has represented high profile criminals such as Antonie Dixon who went of a methamphetamine-fuelled rampage with a samurai sword through Auckland in 2003.

The five-member tribunal - chaired by Judge Dale Clarkson - found Hart had also failed to tell his clients about his fees.

In 2008, a sister of one of his clients said Hart was "evasive" about fees and "did not give any clear guidance at all" as to the fee structure.

Hart, however, did ask about family assets and whether they had a freehold home. The sister borrowed the money from a relative and gave him a cheque for $10,000 the next day at court.

Though he only appeared before a judge for three minutes, he charged the family for seven hours work - including for two hours "preparation".

The tribunal said there was no evidence why Hart did not ask the registrar to have the case called promptly at the start of the day or why an "experienced practitioner would require two hours to prepare".

"Mr Hart was cavalier in his professional responsibility," Judge Clarkson said.

The standards committee will  now file its submissions on Hart's potential punishment.

He could not be reached for comment.

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