If the letter was really written by Thetard, and if "JZ" was Jacob Zuma, then he should resign immediately

The most important question about deputy president Jacob Zuma does not concern the motivations of this or that faction, or whether one agency or another is leaking stories to the press. It is whether documentation first reproduced in the newspapers in December 2002 is authentic and accurate.

At the end of last year, the Mail & Guardian published a photograph of an English translation, commissioned by the Scorpions, of a letter originally in French from Alain Thetard, formerly of Thomson SA. The letter indicated that the company promised an individual referred to as "JZ" an annual payment of R500 000 for protecting Thomson during the "current investigations". If the original letter was really written by Thetard and if the "JZ" mentioned was Zuma and if Zuma was aware of such an agreement, then he should resign immediately. The letter suggests that Schabir Shaik was the go-between in these transactions: apparently it was among the documents seized at Shaik's home.

Oddly, the two extensive interviews with Shaik published by Independent newspapers last week did not refer explicitly to this letter. Perhaps the letter is a forgery or maybe Shaik was using Zuma's name without the deputy president's sanction: these, presumably, are the issues that the Scorpions are trying to resolve. Given the unlikelihood of co-operation from any of the people concerned, it is not surprising their investigation is taking such a long time.

Further allegations against Zuma, of a much less important character, as well as the leaking of the questions the Scorpions have formally asked Zuma to answer, seem to have prompted the present feuding between the ANC and director of public prosecutions Bulelani Ngcuka.

ANC secretary-general Kgalema Motlanthe is angry about a briefing the Scorpions provided for senior editors. Zuma himself has suggested that the leaks were "unacceptable and despicable". There has been speculation about more discreet kinds of executive pressure directed at Ngcuka to drop the investigation, including President Thabo Mbeki's suggestion that the unit might be placed under police authority. To his credit, justice minister Penuell Maduna has defended the Scorpions.

Zuma has every right to be annoyed about the leaks: officials should not give copies of documents concerning the investigation to newspapers before any formal charges are formulated. However, such indiscretions are a normal feature of democratic political life, particularly if officials involved in such investigations have any reason to believe that political pressure will be used to restrict their scope - a reasonable supposition, given the history of the arms contract investigation to date.

Of course there could be other factors prompting such indiscretions. One problem that arises from the ANC's policy of "deploying" its cadres so widely across the bureaucracy is that so many top positions are filled by politically motivated and politically connected people - and so leaks themselves could well reflect political tensions within the organisation.

One theory is that a "hard-line" faction in KwaZulu Natal is intent on embarrassing Zuma. In other words, supporters of regional ANC leaders such as Dumisane Makhaye and S'bu Ndebele aim to discredit that grouping within the ANC that favours conciliation and cooperation with the IFP. Zuma plays a key role in maintaining civilities with the IFP. Makhaye and Ndebele were compelled to back down from confrontation with provincial premier Lionel Mtshali recently: Zuma's influence in this setback for them was decisive. How provincial ANC notables or their supporters are able to obtain access to Scorpion documentation is not clear, though.

Another similar sort of explanation of the ANC's current leaky propensities is that this is one more instance of the competition between former exiles and veteran supporters of the former United Democratic Front (UDF).

An elaboration of this argument is that efforts to attract public attention to the Scorpions' investigation of Zuma are connected with the ANC's succession politics. People who would welcome a competitive procedure would like to open up the deputy presidency for rival claims before the next election. Top ANC leaders would certainly prefer to avoid that.

The ANC's gossipy propensities are a signal of its democratic settling-down, of the final stages of its transition from revolutionary vanguard to a catch-all political party. Scandals come and go in parliamentary democracies: it is how people react to them that signals our state of political health.

Tom Lodge is professor of politics at the University of the Witwatersrand

With acknowledgements to Tom Lodge and the Financial Mail.