A parliamentary estimates committee has admonished Tax Commissioner Chris Jordan for his attack on two tax office whistleblowers, telling him it was an inappropriate use of parliamentary privilege.
"Your opening statement was highly unorthodox and not constructive to the Senate estimates process," the economics legislation committee chairman, Liberal senator Slade Brockman, wrote to Mr Jordan.
"The use of the estimates platform, and the parliamentary privilege that comes with it, to respond to media reporting of the Shamir and Boyle cases was not the appropriate forum to deal with the issue."
Mr Jordan attacked Ron Shamir and Richard Boyle in a hearing in October, accusing them of repeatedly seeking out the public eye, and making potentially damaging claims about the tax office.
They had not been sacked for their whistle-blowing, but because of "ongoing workplace performance or conduct issues that were close to finalisation and likely to result in their termination", Mr Jordan said. He accused Mr Shamir of "persistent and inappropriate behaviour" and Mr Boyle of breaching tax secrecy and listening device laws.
The committee offered the two whistle-blowers rights of reply, and both men have now written back.
Mr Shamir said he would not engage in a public brawl, but would provide material to the committee privately.
"A public response detailing why the commissioner is incorrect is what anyone in my situation would be expected to do, to defend their reputation," he wrote.
"However, to do that would be to engage in a public brawl, and as a former public servant I am not going to bring that role into disrepute by engaging in that conduct.
"It will be for the committee to form a view about the commissioner's statement."
Mr Boyle's lawyer, Sarah Grimwade, declined the offer. He now faces charges relating to his use of documents and recording of calls, with the case in the Adelaide courts now.
"It is our view that nothing that has been said by the commissioner meaningfully addresses the detailed issues Mr Boyle raises in his complaint," she said.
"Indeed, it is unfortunate that the commissioner has chosen to make disparaging remarks against Mr Boyle under the cloak of parliamentary privilege, which has jeopardised Mr Boyle's right to a fair trial."
Mr Boyle's public interest disclosure related to the Tax Office's use of garnishee notices to seize money from people's bank accounts. Mr Shamir's disclosure accused the tax Office of withholding business tax refunds.