The position of the plaintiffs in the proceeding may be contrasted with those whom they represent - the group members. Subject to some exceptions that do not matter for present purposes, the consent of a person to be a group member is not required. Group members may neither know of the commencement of the proceeding nor wish that it be brought or prosecuted, although Pt 4A does provide for notice to be given to group members of (among other things) the commencement of the proceeding.
The Supreme Court may dispense with the giving of that notice if the relief sought in the proceeding does not include a claim for damages and, if notice is to be given, it may be given by press advertisement, radio or television broadcast or any other means. Unless the Supreme Court is satisfied that it is reasonably practicable, and not unduly expensive, to do so the Court may not order that notice of the proceeding is to be given personally to group members. There is, therefore, a real possibility that some group members would remain "perfectly ignorant of the proceedings, and of what is really going on". That is, some of those who would benefit from success in the proceeding (but thereby lose the opportunity to pursue their individual claim in some way, or to some effect, different from the group proceeding) may have their rights affected without their knowing or consenting to that being done.
So much follows from the fact that Pt 4A provides for what is sometimes called an "opt out", rather than an "opt in", procedure. That is, persons who are group members may opt out of the proceeding and, if they do, they are taken never to have been a group member (unless the Court otherwise orders). Group members, however, need take no positive step in the prosecution of the proceeding to judgment to gain whatever benefit its prosecution may bring.
Provision is made for the Court to fix a date before which a group member may opt out and, except with the leave of the Court, trial of the proceeding may not begin before that date. The Court, on the application of a party to the proceeding, or of its own motion, may at any time, before or after judgment, order that a person cease to be, or not become, a group member. The circumstances in which the Court may make such an order are stated in very wide terms. It may do so if it is of the opinion that the person does not have "sufficient connection with Australia to justify inclusion as a group member", or that for any other reason it is "just or expedient" that the person should not be or become a group member. And if a person who is a group member does not opt out, either before or after judgment, a judgment given in the proceeding binds that person along with all other persons who are group members at the time judgment is given.[17] [citations omitted, emphasis added]