The Otago Daily Times understands an investigation began in mid-2023 into Mr Barton’s work in relation to the execution of a will.
News of the complaint comes just a week after the senior lawyer was cleared of any wrongdoing by a standards committee in relation to the destruction of documents by Presbyterian Support Otago (PSO) while he was a board member.
In July last year, New Zealand Law Society vice-president David Campbell said Mr Barton would take a leave of absence "while any complaints are addressed".
When asked whether his position was now untenable, the law society said Mr Campbell could not respond.
A spokesman said it was prohibited "from commenting on whether we have received a complaint, or any details of concerns or complaints raised with us" but had "full confidence" in Mr Barton.
The University of Otago said Mr Barton would remain a member of the University Council.
"We are in discussions with Mr Barton about the matter and have confidence in the Law Society’s processes," a spokeswoman said.
While the ODT has agreed not to publish details of the complaint currently under investigation, it can be revealed that it involves two other lawyers and a source said it was "extensive and complex".
Law society complaints, if successful, go through a five-stage process.
The current investigation is understood to have reached stage three where the committee opts to "undertake an inquiry".
"It can seek additional information, including a copy of the lawyer’s file. It can also appoint a person to undertake an investigation or review," according to law society information.
The controversy surrounding Mr Barton and the PSO stemmed from an email exchange between him and then-CEO Gillian Bremner in February 2016.
She had asked Mr Barton about whether a file alleging abuse while in PSO care should be released to a lawyer — he said yes.
During that email exchange, Ms Bremner later asked "... on balance do you think we are best to destroy the rest of the files and keep only minimal info? The connection is with [name of staff member in charge of looking after the files] and I think when she retires in the next five years we would do just that as we would have no connection and frame of reference to that bit of history and no legal obligation to hold them."
Mr Barton responded one minute later: "Yes, I think so but at an appropriate milestone or anniversary."
The standards committee ruled the lawyer could not have reasonably foreseen that his response would be relied on without follow-up discussion, and also said there was no evidence there had been contemplation of an impending royal commission of inquiry.
University of Auckland ethics professor Tim Dare remained staggered by that conclusion.
"He may not have known about the commission of inquiry, but he knew that the PSO was concerned about people alleging abuse in their care," he said.
"That should have been enough for him, as a member of the PSO board ... and as a lawyer to have told the PSO that they should give priority to the interest of the abuse survivors to obtain redress and compensation."
A law society spokesman said 1231 complaints were received last year which represented about 7% of all lawyers.
More than 80% of complaints resulted in no further action, he said.
