Kiefel CJ
Bell J
Gageler J
Keane J
Nettle J
Gordon J
Edelman J
5.
renouncing the foreign citizenship. That was said to be because a naturalised Australian citizen could be expected, in the ordinary case, to have the requisite knowledge of his or her pre-existing foreign citizenship.
Secondly, the approach urged by Mr Joyce MP and Senator Nash was that s 44(i) requires that foreign citizenship be chosen or maintained. The essence of this approach was knowledge of the foreign citizenship. It was submitted that a person cannot make a choice to retain or renounce any foreign citizenship if he or she has no knowledge of that citizenship. Although the degree of knowledge that was said to apply in this context did not include constructive knowledge, it did include wilful blindness.
Thirdly, the approach urged by Mr Ludlam and Ms Waters was that s 44(i) requires that a person be "put on notice". On this approach, the person would be disqualified under s 44(i) if he or she had knowledge of facts that, in the mind of a reasonable person taking a properly diligent approach to compliance with the Constitution, ought to call into question the belief that he or she is not a subject or citizen of a foreign power and prompt proper inquiries. Knowledge would include, at least, knowledge of "primary facts" that would prompt inquiry and, at most, all of the knowledge of the person.
By way of a variation on the Attorney-General's principal theme, it was said that s 44(i) applies only to a person who has by voluntary act acquired foreign citizenship, or exercised a right pursuant to the status of foreign citizenship, the latter being a way of describing an overt act of retention of foreign citizenship.
The approach urged by the amicus and on behalf of Mr Windsor must be accepted. It adheres most closely to the ordinary and natural meaning of the language of s 44(i). It also accords with the views of a majority of the Justices in Sykes v Cleary, the authority of which was accepted by all parties. A consideration of the drafting history of s 44(i) does not warrant a different conclusion. Further, that approach avoids the uncertainty and instability that attend the competing approaches.
The text and structure of s 44(i)
As to the text and structure of s 44(i), in Sykes v Cleary Brennan J said that "[p]utting acknowledgment of adherence to a foreign power to one side",
