Is s 494AB about jurisdiction? Or does it rather provide the Cth a defence?

Some of the questions to the High Court (HCA) were as follows:

Question 1: Can it be said that s 494AB of the Migration Act 1958 (Cth) does not take away the jurisdiction of any court to hear and determine proceedings of the kinds described in s 494AB(1), but rather provides the Commonwealth with a defence to those claims if they are made in a court other than the High Court?

Question 2: If the answer to Question 1 is "yes", does s 494AB provide an answer or defence to those types of claims if they are brought in the High Court?

Question 3: If the answer to Question 2 is "no", could proceedings instituted in the High Court in relation to the matters identified in s 494AB(1) be remitted to another court for hearing and determination without s 494AB providing an answer or defence to the claim?

Question 4: If the answer to Question 3 is "yes", does that corroborate the argument that the answer to Question 1 above should be "yes"?

Question 5: Can it be said that "s 494AB provides for an answer (analogous to a time bar) which the Commonwealth may plead to a claim of a kind identified in s 494AB, when and if pleading the answer would be consistent with its model litigant obligations?

Question 6: Can it be said that the operation of s 494AB "is not restricted to identified kinds of claims or causes of action, or to claims for particular forms of relief", with the consequence that "the section does not exclude all common law negligence cases against the Commonwealth"?

Question 7: Is 494AB confined in its application to proceedings in the nature of judicial review?

Question 8: Does s 494AB its terms apply to any and every proceeding relating to regional processing?

Question 9: Is s 494AB confined to: "proceedings which challenge the actual or threatened exercise of, or failure to exercise, power; proceedings which challenge the validity or scope of provisions of the Migration Act; or proceedings in which the Migration Act is expressly invoked or relied upon"?

Question 10: In the context of assessing whether ss 494AB(1)(a) or (ca) apply, does the legislative text and context "require some further inquiry into whether the actions taken under Subdiv B [Division 8 of Part 2 of the Migration Act] also had the capacity to, or did, affect legal rights"?

Question 11: Can it be said that, "where proceedings are brought in which the transfer of a transitory person to Australia under s 198B of the Act is raised as an issue between the parties, they will be "proceedings relating to" the exercise of powers under s 198B and attract the operation of s 494AB(1)(a)"?

Question 12: Can it be said that, "in deciding that there is an issue between the parties attracting s 494AB(1)(a), it will not always be necessary for s 198B to be expressly identified in the pleadings (or if there are no pleadings, the application and other filed documents)"?

Question 13: If the answer to Question 12 is "yes", should the issue nevertheless be raised for determination by the court?

The HCA answered those questions as follows: