Pretoria - After failing to file its head of arguments in the so-called "spy tapes" case last month, the National Prosecuting Authority finally did so on Friday.Spokesperson Luvuyo Mfaku said the documents were filed in the High Court in Pretoria. The papers were in response to the Democratic Alliance's bid to review the decision to have corruption charges against President Jacob Zuma dropped in 2009.The DA brought the application after it was handed the tapes last year. The Supreme Court of Appeal ruled that the NPA had to comply with a previous order to release the tapes. Zuma had opposed the move. The DA believes the tapes, which contain recorded phone conversations, justify proceeding with a review application of the decision to drop the charges against Zuma.The tapes allegedly reveal collusion between the former head of the directorate of special operations - the now defunct Scorpions - Leonard McCarthy, and the NPA's former head Bulelani Ngcuka, to manipulate the prosecution of Zuma before the ANC's Polokwane conference in 2007.The charges related to Zuma's allegedly receiving a bribe from French arms company Thales via his former financial adviser Schabir Shaik, who was jailed for corruption. He was released on medical parole in 2009.Zuma was elected ANC president at the Polokwane conference. Former president Thabo Mbeki had been a contender for a second term and the contest for the top position caused rifts in the party. The Scorpions were also subsequently disbanded.Political conspiracy against ZumaThe corruption charges were dropped shortly before Zuma was sworn in as president in 2009.The then-acting national director of public prosecutions Mokotedi Mpshe claimed the tapes revealed a political conspiracy against Zuma, and so the case could not continue.The DA contends Mpshe could not have rationally concluded that McCarthy manipulated the timing of the service of the indictment to suit Mbeki, since the evidence indicates that Mpshe made the decision to delay the service of the indictment himself. The party says McCarthy played no material role.In its head of arguments however, the NPA says there was no connection between information known to Mpshe and his stated reasons for discontinuing the prosecution. The NPA says Mpshe had no power to institute a prosecution. "Had he purported to do so, that decision would have been invalid. The legal authority to institute a prosecution vests with DPPs [directors of public prosecutions]. "In this case it vested with McCarthy. Secondly, as a fact, McCarthy was in charge of the Zuma prosecution. The prosecuting team reported to him. They took instructions from him. He made all decisions about the prosecution, including the decision when to institute the prosecution," the heads of argument read. The NPA listed several reasons why Mpshe decided not to continue with the case. They include that Zuma's legal team was able to substantiate its claims about the political manipulation of the NPA. 'A serious abuse of process'After investigating, Mpshe concluded that McCarthy had abused the legal process for a purpose extraneous to the Zuma prosecution."McCarthy used the legal process for a purpose other than that for which it was intended. More particularly, he manipulated the timing of the prosecution for a purpose unrelated to the prosecution," the NPA says in its heads of argument."McCarthy’s conduct amounted to a serious abuse of process and offended his sense of justice. In these circumstances it was neither possible for Mpshe nor desirable for the NPA to continue with the prosecution of Zuma."The NPA maintains there was no link between the decision to discontinue the prosecution, Mpshe’s reasons, and the purpose of Mpshe’s power."Mpshe stopped the prosecution on policy grounds. McCarthy’s conduct perverted the constitutional guarantee of prosecutorial independence. Mpshe felt that it was unconscionable to continue the prosecution in these circumstances," the NPA says.