Background
4 These proceedings have had a very long history. A number of the individual Tibra parties had previously been employed by one or other of the Optiver parties before leaving between November 2005 and June 2006. In some cases those individuals co-operated in the formation of, or worked in, the Tibra parties' businesses.
5 On 19 June 2007, Optiver commenced some preliminary discovery proceedings in this Court against some of the present Tibra parties. Those proceedings led to the commencement of the present proceedings on 8 July 2009. The present proceedings were case managed by Emmett J for a considerable time until early 2012. During the course of that case management, his Honour ordered the Optiver parties to file a statement of the nature of their case by 30 September 2009 in order to give further clarity to the allegations made in the statement of claim. That document was amended twice, and on 16 November 2010 the present further amended statement of the nature of the case was filed by the Optiver parties.
6 On 16 February 2012, the Optiver parties wrote to the Tibra parties seeking consent to make the same amendment as is now sought. In essence, the amendment seeks to identify the generic market interface program as a separate copyright work. Following an exchange of correspondence between solicitors for the parties, the Optiver parties, having failed to gain consent to the proposed amendment, filed an interlocutory application on 5 March 2012 to amend their statement of claim. On 14 March 2012, the Optiver parties amended that application to seek leave to add the gmi program to the list of programs in the statement of the nature of their case. However, on 19 March 2012, the Optiver parties' solicitors notified the Court and the Tibra parties' solicitors that the Optiver parties no longer wished to press that interlocutory application. On the next day, I ordered that it be dismissed with costs. The matter then took a number of procedural developments to which I have referred in earlier judgments: see Optiver Australia Pty Ltd v Tibra Trading Pty Ltd (No 4) [2012] FCA 731; Optiver Australia Pty Ltd v Tibra Trading Pty Ltd (No 6) [2012] FCA 1503.
7 On 19 June 2013, the Optiver parties filed the present interlocutory application seeking leave to add to the statement of the nature of their case, the generic market interface, as a program in its own right together with one source code in respect of it. Maurice Gonsalves, the solicitor for the Optiver parties, swore an affidavit on 19 June 2013 in support of that amendment. He said that he had reviewed with counsel a number of aspects of the Optiver parties' case with a view to ensuring that all necessary pre-trial steps were taken in good time before the start of the final hearing.
8 I had set the hearing down, at the joint request of the parties, to commence on 10 March 2014, so that it would run until it concluded. The parties had refused my suggestion that the proceedings could be set down for trial in about August 2013 on the basis that they wish to retain counsel and those involved to date, in a final hearing and that could not conveniently be accommodated before 10 March 2014. Mr Gonsalves said that the decision taken on 19 March 2012 not to press for the amendment to include the generic market interface as a separate program in the statement of the nature of their case at that time was made "primarily because of the short time before the final hearing was due to commence". He said that following the more recent pre-trial review he came to the opinion that in light of the vacation of the reference that I had ordered, and the fact that the hearing was not now due to commence until March next year, the amendment should be formally pleaded. He said that in his view it would not cause any prejudice to the Tibra parties, particularly because gmi had always been pleaded as a component of the Optiver programs alleged to have been infringed, as well as having been the subject of extensive expert evidence on both sides.
9 The Optiver parties pointed out that a great deal of lay and expert evidence has dealt with the directories forming part of the source codes for the 14 programs in which the generic market interface was a component. The Optiver parties do not seek to lead any further evidence-in-chief on this topic. They assert that their case depends on drawing together inferences from the way in which the lay and expert witnesses had dealt with the operation of the generic market interface, and the alleged copying of it in respect of the various components of its previously identified 14 programs. Indeed, Professor Zobel, one of the Optiver parties' experts, opined that in respect of a program known as F1, the gmi component appeared to have been extensively copied in the Tibra parties' version of a program performing similar functions. He noted that the gmi and the Tibra equivalent, called "XI", components were of central importance in the suites of programs of each of the parties' computer software.
10 The Tibra parties' solicitor, Sue Gilchrist, swore an affidavit in opposition to the amendment. She observed that it would be necessary for the Tibra parties' solicitors to work with their clients, counsel and experts on the issues, first, of whether gmi constituted a set of statements or instructions to be used directly or indirectly on a computer in order to bring about a certain result, and, secondly, the substantiality of the allegedly copied portions of the code in connection with the consideration of whether or not gmi was a separate program, as opposed to forming part of or being a component in the 14 identified programs. Ms Gilchrist anticipated that it would be necessary for her clients to prepare and file further evidence on those issues, including the need for further expert joint reports and conferences. She observed that the addition of the gmi program as a matter in issue would need exploration at trial and expand the issues in dispute. Ms Gilchrist said that one of the Tibra parties' experts, Dr Wilson, had deposed that gmi contained 35 files, and amounted to approximately 2.7% of the code in the Optiver code base. She observed that, based on Dr Wilson's evidence as to the extensiveness of the gmi files and other material, if gmi were treated as a separate program, it would be about a quarter of the size of the next smallest copyright work relied on by the Optiver parties. She observed that Dr Wilson had only limited availability. He had now engaged in full-time employment and was no longer available outside his private time to act as an expert witness. She suggested that it would not be possible to finalise evidence from Dr Wilson until at least early December 2013, were he asked to deal with this new aspect of the case.