EXTERNAL AFFAIRS POWER The Commonwealth executive has an inherent power to ratify international treaties however a ratified treaty needs to be incorporated into domestic law to become enforceable.1 Section 52 (xxix) of the Constitution confers power on the Commonwealth to legislate with respect to “external affairs”. It has been established that the Commonwealth can implement treaty obligations under s51(xxix) regardless of subject matter, when related to a matter of “international concern”.2 The International Convention on the Prevention of Terrorism is a valid multilateral treaty and can be implemented into Australian domestic law. It has been indicated in a number of High Court decisions that the Commonwealth can only implement treaties entered into in good faith, not “merely as a means of conferring legislative power upon the Commonwealth”.3 Establishing that the treaty was not bona fide would be difficult to establish4 and unlikely to prove the legislation unconstitutional. The Tasmanian Dam case indicated that “the Commonwealth cannot use s51(xxix) to implement treaty provisions which impose no actual obligation on state parties”.5 Both Article 1 and Article 2 of the treaty impose actual obligation on the Commonwealth and the legislation could not be deemed unconstitutional on the “obligation” issue. This is irrelevant however, as Victoria v Commonwealth (the ILO case)6 overturned the notice of “obligation” and replaced it with a “specificity” criterion. The majority in the ILO case stated that “when a treaty is relied on under s51(xxix) to support a law, it is not sufficient that the law prescribes one of a variety of means that might be thought appropriate and adapted to the achievement of an ideal. This case also highlights the importance of whether the treaty is reasonably specific as to what states are expected to do. In this case the treaty obligation is to ‘take appropriate measures with a view to preventing terrorist offences’. Preventing terrorist offences can arguably be achieved in a large number of ways and there is no specific domestic or international method. This treaty gives the Commonwealth a large amount of discretion as a specific regime is not given to guide them in implementing the treaty. It is obvious that the distinction between sufficient and insufficient specificity is difficult to ascertain. More recent case’s have helped to clear this distinction, especially Thomas v Mowbray (2007).7 According to the principles of this case, the phrase “take appropriate measures with a view to preventing terrorist offences and their negative effects” could parallel with the phrase used in the Thomas v Mowbray decision as a “phrase of almost limitless reach”.8 This case “noted the different paths taken by UN member nations to combat terrorism”9 and that on this ground the treaty could fail the specificity test. Another test used in assessing the validity of the external affairs power is the conformity principle. This principle arises with regard to the nature of the implementing legislation.10 The conformity principle prescribes that “legislation will not be authorised as an exercise of treaty implementations under s51(xxix) if it plainly undermines the object and purpose of the treaty”.11 The purpose of the treaty is to take effective measures to prevent terrorism. The legislation must be based around the purpose or object of the treaty and hence why it has been noted that the external affairs power has ‘a purposive aspect’.12 The legislation to request warrants for detention as well as the legislation monitoring suspicious financial activity could be seen as “reasonably capable of being considered appropriate and adapted to achieving the purpose or object of giving effect to the treaty”.13 In regards to Colony’s claim, it would be unlikely that he could deem either piece of legislation unconstitutional on the scope of the external affairs power. The Commonwealth has extensive scope under