Whilst acknowledging the width of the statutory phrase in the Act which requires that the Minister's nominee should simply be a "person", the plaintiffs submitted that the word had to be read down in its context so as to exclude federal judges. The argument went thus. The Act is written against the background of the Constitution which includes, as a foundation principle, the separation of the judicial branch of government from the legislative and executive branches. Parliament could be taken to know of, and to respect, this separation. Its legislation would reflect the principle. Where Parliament intended, as an exception to the principle, to involve federal judges as designated persons to perform non-judicial functions within the Executive, it would expressly so provide. So it had done under the Telecommunications (Interception) Act 1979 Cth considered in Hilton [80] and Grollo [81] . Where Parliament envisaged the use by the Executive of a person who, in that person's principal capacity exercised the judicial power of the Commonwealth, it would, and should, so provide expressly. It would spell out provisions for the detachment of such a judge from the federal court in question [82] . It would provide for the tenure of the judge notwithstanding such appointment [83] . It would afford the judge protection from suits of defamation and immunity from civil liability such as is normal to the performance by a judicial officer of the kind of functions assigned to, or performed by, him or her. Normally, although not universally, the judge might be expected to perform the duties of office in public. It was acknowledged that Royal Commissions sometimes, and "eligible judges" performing duties under the Telecommunications (Interception) Act always, departed from this public feature of judicial activity. Usually, although not always, where a judge of a court enjoying the prestige of the Federal Court of Australia was to be involved, in effect, in the provision of advice to the Executive Government, the appointment would be made not by a letter from a Minister but by formal instrument of the Federal Executive Council, envisaged by a statute and published in the Gazette . The judge's report would have a formal status. Although advising the Executive, it would typically be more than a mere pre-condition to the exercise of a Ministerial statutory power. The expectation of a clearer provision, greater specificity and more detailed incidents of the appointment of a judge of a federal court did not rest upon arguments of prestige and status alone. Such provisions recognised the importance of the reality, and appearance, of judicial independence. They imposed a control on any risk of debasement of the separation of the judicial from the other branches of government which, it could be assumed, the Parliament would wish to preserve. They also provided a break on the willingness of some judges to involve themselves in the interesting, but risky and controversial, tasks of the Executive as a relief from the unrelenting work of judicial life. Consistent with the doctrine expressed by the Court in Hilton and Grollo , Parliament could provide for the assignment of Executive functions to federal judges who were willing to perform them as designated persons. But it should do so expressly, clearly and under proper conditions. Where it did not, constitutional principle and the rule protective of the independence of the judicial branch of government would oblige a construction of the legislation such that general words (person) were read down as not applying to a federal judge.