The Supreme Court of Victoria Court of Appeal yesterday rejected a bid by National Australia Bank to require 20 out of 250 plaintiffs in a class action to produce documents regarding how they made their investment decisions.The plaintiffs are seeking damages arising from a loss in the value of NAB's shares, following the disclosure of losses on collateralised debt obligations in late 2008. International Litigation Funding Partners is funding the case, with Maurice Blackburn managing the case, which is due to go to trial in December.NAB wanted access to documents from the 20 largest shareholders in the case that disclose the documents available to them on NAB's investment in CDOs and sub-prime securities.The trial judge in the class action has already ruled that there are no grounds to produce the documents. The appeal court agrees.Justice Kevin Bell, in a judgement for the three-member panel, wrote: "Usually the plaintiffs conduct such a proceeding on behalf of themselves and the group members who might stand to benefit from the outcome.""The group members (in this case, the market participants) usually play a passive role and discovery orders are not made against them unless, for example, it is reasonably necessary for the conduct of the defendant's case. "It was open to his Honour to decide that the bank had not established sufficient grounds for departing from the usual course in the present case."