The Judicial Service Commission needs to conduct an open interview to assess the suitability of President Jacob Zuma's nomination of Judge Mogoeng Mogoeng as chief justice, says DA leader Helen Zille.

The Democratic Alliance's representative on the JSC, Hendrik Schmidt, would motivate for such an interview to take place within the next week, she said in a statement on Wednesday.

Schmidt would also request that the president make available the information he considered, as well as the reasons for nominating Mogoeng as his preferred candidate ahead of other potential candidates.

"The appointment of a chief justice is a decision that requires the most careful and detailed consideration.

"To ensure that the consultative process envisaged in section 174 of the constitution is meaningful, we believe that the president's nominee should be interviewed and interrogated in the same way that all judicial appointees are."

This was precisely why previous nominees for the position of chief justice had been interviewed by the JSC.

A number of interested parties as well as members of the legal fraternity had expressed concerns at Zuma's nomination of Mogoeng.

"It is therefore appropriate that he is given an opportunity to address these concerns in an open hearing," Zille said.

Zuma nominated Mogoeng on Tuesday to replace former chief justice Sandile Ngcobo, whose term of office expired on Sunday.

In terms of the constitution, Zuma has to appoint the chief justice after consultation with the JSC and leaders of parties represented in the National Assembly.

National Association of Democratic Lawyers (Nadel) spokesman Nokukhanya Jele said Nadel looked forward to the JSC announcing the process to be followed in receiving additional nominations and submissions, and the manner in which candidates for this important position would be processed.

"Nadel hopes that by the end of this process the JSC will present the president with a rich list of some of the most qualified and suitable candidates in order for the president to choose the candidate most suited to take on the considerable responsibilities of the office of the chief justice," Jele said.

It is not clear whether a call can be made for other candidates.

Earlier this month, JSC spokesman Dumisa Ntsebeza said the relevant section seemed to envisage a consultative process but he was not sure that it envisaged an invitation to apply for, or to receive applications for the position.

"...nor has that ever happened in this country before," he said.

Former president Thabo Mbeki nominated former chief justice Pius Langa and deputy chief justice Dikgang Moseneke without a call for nominations.

Ngcobo was interviewed at JSC hearings in Kliptown, Soweto, in September 2009 after earlier being identified by Zuma as "preferred candidate" for chief justice to succeed Langa.

Pretoria University law faculty's Centre for Human Rights questioned Zuma's nomination of Mogoeng.

The basis for his nomination was "startlingly unclear", it said.

At the time of Mogoeng's appointment to the Constitutional Court in October 2009 concerns were raised about his lack of experience in constitutional matters.

The centre pointed out that Mogoeng had written minority opinions in, among others, the Glenister case, upholding legislation abolishing the Scorpions.

"Surprise and lack of persuasive substantiation breed suspicion," the centre said.

"The obvious question is: Why was the obvious or any of the other more experienced candidates not selected?"

If appointed, it would be up to Mogoeng to dispel any perception or suggestion that his unexpected appointment signalled "an attempt at executive corrosion of the independence of the judiciary".

"The president need not heed any misgivings expressed about the basis and lack of convincing reasons for his choice.

"However, he should at least seriously consider the views of opposition leaders and especially the JSC.

"We therefore encourage the JSC to consider the gravity of its role, conscious that the appointment of a chief justice should not, in the first place, serve the interest of an incumbent government (or President), but that of the state as a whole," the centre said.