Cape Town - There are very few substantive reasons that Speaker of Parliament Baleka Mbete could cite for dismissing a bid to hold a motion of no confidence in the president via secret ballot, an expert says.The Constitutional Court on Thursday ruled that Mbete, as speaker, does have the constitutional power to decide whether or not to hold a secret ballot for a motion of no confidence in President Jacob Zuma.Mbete definitely had the power to say no to a secret ballot, but under the circumstances, it would be highly irrational for her to do so, Centre for Constitutional Rights director Phephelaphi Dube told News24 on Thursday."The Constitutional Court has said that the rules of Parliament do allow for a secret ballot, and Baleka Mbete herself has admitted she is not opposed to a secret ballot," Dube said."So the question going forward is whether she is going to make a rational decision, and allow a secret ballot to take place."There is almost very little reason for her to turn down a secret ballot."Chief Justice Mogoeng Mogoeng on Thursday was at pains to express that all public power must be exercised rationally, Dube said, and that it was ultimately Parliament's job to hold the executive to account in the best way it deemed fit, and in the interests of the public.MPs were also beholden to the Constitution, first and foremost, and then their parties.'It will be very difficult for her to make a U-turn'In order for Mbete to turn down the request, her reasons would need to be rational, and in line with the court's ruling and the Constitution, Dube continued."She could turn it down on, maybe, procedural grounds only. She could say they do not have enough capability in Parliament to put in place a secret ballot at short notice."Beyond that, though, there are no substantive reasons to say no, especially since she herself is on record as saying she was okay with the idea [in principle]. It will be very difficult for her to make a U-turn, given her initial stance."Mbete on April 11 said, as speaker, that she "holds no position" on the request to hold the motion via secret ballot.On Thursday, Parliament repeated that the Speaker of the National Assembly had no personal or principled opposition to the use of a secret ballot.They would "give effect to the ruling", now that the speaker's role had been clarified, essentially meaning Mbete will make a decision in due course.Dube said the parties would now go back to the drawing board, in view of the motion being scheduled at the soonest possible date, as requested by the Democratic Alliance.She anticipated court action from opposition parties, on the basis of rationality, if Mbete turned down the request."The fact that all exercise of public power should be exercised rationally, we will probably end up in the courts again to ask ourselves, was that a rational decision [if it is turned down]."'We are still growing as a country'The ANC in Parliament on Thursday welcomed the court's ruling, saying it did not change the party's expressed position that it would not vote against Zuma either way.ANC chief whip Jackson Mthembu said the ruling reminded the country that our electoral system was a party political system, and therefore members derived their mandates from their party's constitutions.Dube, however, said Mthembu's comments only applied in cases where the Constitution was not contravened."All of what the chief whip said is quite correct. The bottom line though is that party members are still beholden to the Constitution. So, even if they are elected via parties, it still needs to be within a Constitutional framework."So his comments fell short of the Constitutional imperative."Dube added that the ruling showed the country was maturing as a democracy."Just yesterday, we didn't know whether or not a secret ballot was possible, and today that question has been clarified by the Constitutional Court," she added."We are only 23 years old and we are still growing as a country."