His Queen's Counsel, Paul Davison, said Whale did not contest the charge brought by the Law Society that his convictions amounted to conduct that would tend to bring the profession into disrepute.
While his client's actions as a director had been "found wanting", Davison said the Law Society had "seized upon" the "gross negligence" description in order to treat Whale the same as convicted Bridgecorp chairman and lawyer Bruce Davidson.
Davidson was last year suspended from practising as a lawyer for nine months.
Although admitting there were similarities between the two, Davison said there were "significant differences which favour Mr Whale's position as being one which is less serious and less egregious".
But Peter Davey, acting for the Law Society's Auckland Standards Committee, said a period of suspension similar to Davidson's was appropriate, although Whale did have the advantage of admitting the allegations.
Davey submitted that Whale should be suspended for at least seven months.
While Whale had not renewed his lawyer's practising certificate following his conviction, he told the tribunal had been doing legal work similar to that of a legal executive or a law clerk for Jones Young, the firm he was a partner of prior to his conviction.
Whale would be unable to continue that work if suspended, Davey told the tribunal.
Whale's appearance before the tribunal was the culmination of "what's been an enormous ordeal" for a man who was well regarded as a lawyer, said Davison.
While not wanting to minimise the impact on investors who lost money, Davison said the collapse had "disastrous consequences" for Whale in "in terms of his professional work, in terms of his personal life and financially."
Davison said his client came before the tribunal "humbled and embarrassed" and that Whale's suspension was an "inevitable event".
"Mr Whale has been through an enormous ordeal. He's been confronted with charges of committing a crime with all of the negative and moral condemnation that an allegation of criminal conduct carries with it. Notwithstanding the crime he was charged with did not involve any dishonesty," Davison said.
Earlier during the hearing, tribunal member Graham McKenzie probed the claim Whale had not been dishonest.
He referred to a comment from Justice Dobson during sentencing on "an instance of apparent dishonesty" concerning an email Whale sent about related-party transactions to the company's auditors in 2008.
The judge said to Whale during his sentencing that the email "was flat out wrong, and you knew it to be".
Whale told the tribunal the email was clearly wrong but that he was not deliberately trying to mislead anyone.
Other questions from the tribunal focused on Whale's financial position and why he had offered a reparation of $75,000 when fellow guilty director Ann Butler put forward $300,000.
Whale was asked whether he debated with family members selling some assets from trusts - which own his home and a share in a beach house - so more reparations could be offered.
This was discussed but was vetoed by trustees, Whale said.
At other times, Whale was queried about conflicts in the board room and whether he ever considered resigning over them.
"As to my dying day I will regret not resigning," Whale told the tribunal.
The tribunal reserved its decision.
