President Cyril Ramaphosa has appointed advocate Azhar Bham as the presiding officer in the disciplinary inquiry into suspended Sars commissioner Tom Moyane.
Ramaphosa had initially appointed Judge Kate O'Regan to preside over the inquiry.
"This follows an objection raised by Mr Moyane regarding the links between judge Kate O'Regan, who had initially been appointed as the presiding officer, and Corruption Watch, an NGO of which she is a board member," the presidency said in a statement on Tuesday.
"While the president is certain that Judge O'Regan would have adjudicated the matter objectively and that her position did not present a conflict, he decided that it would nevertheless be important to remove any possible perception of bias."
Moyane's legal team told the presidency last week that they will head to court over a technical aspect of his disciplinary inquiry.
Moyane's lawyer Eric Mabuza told Fin24 that they informed Ramaphosa's office on Wednesday of their intention to challenge the written-evidence aspect of the inquiry.
The suspended Sars commissioner, who maintains he's innocent of the 12 misconduct charges he faces, insists he should be allowed to make oral representations. Moyane's legal team has written to Ramaphosa arguing against the disciplinary inquiry being held in writing, as the Sars Act allows for oral evidence.
According to the disciplinary hearing's terms of reference, oral evidence would be heard only at the panel chair's discretion.
The lead-up to the disciplinary inquiry, the date of which has yet to be determined, has been increasingly acrimonious. Ramaphosa has turned down several of Moyane's demands, including a request that the state cover Moyane's legal costs.
Moyane's team alleged a conflict of interest on O'Regan's part, owing to her role in Corruption Watch.
The civil society organisation said in March that it would pursue a private prosecution against Moyane if the National Prosecuting Authority failed to act.
Ramaphosa suspended Moyane on March 19, accusing the Sars commissioner in his suspension letter of contributing to the "deterioration in public confidence at Sars and public finances being compromised".
Corruption Watch executive director David Lewis told Fin24 on Friday that the organisation is not commenting on the issue.