Disposition of the appeals
56 Neither appellant contended that the Determination was made for an unauthorised purpose or was void for unreasonableness. Their legal challenge was and is one of simple ultra vires. The general approach to such a challenge was described by Rich J in Footscray Corporation v Maize Products Pty Ltd (1943) 67 CLR 301 (Footscray Corporation) at 308 as follows:
Authorities are of little use in determining the validity of a particular by-law. The appropriate steps are to construe the statute under which the by-law is made and then interpret it to ascertain whether it is within the ambit of the statute.
Although those observations were directed to a local government by-law, we consider that they apply to any subordinate legislative instrument, including the Determination.
57 The focus must necessarily be on construing the enabling statute and then construing the relevant subordinate legislative instrument to determine whether it is within the enabling power. As noted above, the primary judge set out relevant extracts from recent High Court decisions in which the Court has emphasised the importance of consideration of the text itself in the task of statutory construction, while also noting that the statutory text must be considered in its context, which can include legislative history and extrinsic materials. The extracts included the following passage from Alcan at [47] per Hayne, Heydon, Crennan and Kiefel JJ, which is frequently cited:
This Court has stated on many occasions that the task of statutory construction must begin with a consideration of the text itself. Historical considerations and extrinsic materials cannot be relied on to displace the clear meaning of the text. The language which has actually been employed in the text of legislation is the surest guide to legislative intention. The meaning of the text may require consideration of the context, which includes the general purpose and policy of a provision, in particular the mischief it is to seeking to remedy.
58 The primary judge noted that this passage from Alcan was repeated by French CJ and Hayne J in Certain Lloyd's Underwriters Subscribing to Contract No IH00AAQS v Cross [2012] HCA 56; (2012) 248 CLR 378 at [23] and their Honours' further statement at [24] (footnotes omitted):
The context and purpose of a provision are important to its proper construction because, as the plurality said in Project Blue Sky Inc v Australian Broadcasting Authority, "[t]he primary object of statutory construction is to construe the relevant provision so that it is consistent with the language and purpose of all the provisions of the statute" (emphasis added). That is, statutory construction requires deciding what is the legal meaning of the relevant provision "by reference to the language of the instrument viewed as a whole", and "the context, the general purpose and policy of a provision and its consistency and fairness are surer guides to its meaning than the logic with which it is constructed".
(See also Consolidated Media Holdings at [39]; Federal Commissioner of Taxation v Unit Trend Services Pty Ltd [2013] HCA 16; (2013) 87 ALJR 588 at [47]; Thiess at [22]; CPCF v Minister for Immigration and Border Protection [2015] HCA 1 at [88]-[89] and CIC Insurance Ltd v Bankstown Football Club Ltd [1997] HCA 2; (1997) 187 CLR 384 (CIC Insurance) at 408 per Brennan CJ, Dawson, Toohey and Gummow JJ).
59 The task of construing the Act and the Determination is further assisted by some other general principles of statutory construction. As noted above, the primary judge made reference to some of these principles, including principles guiding the construction of definitional provisions; the requirement of s 11B(1) of the Acts Interpretation Act that an amending Act be construed with the amended Act and the requirement that delegated legislation, such as the Determination, must conform to the purposes for which it is enabled.
60 On the third of those matters, the primary judge made reference to Swan Hill Corporation and R v Toohey; Ex parte Northern Land Council [1981] HCA 74; (1981) 151 CLR 170 (Northern Land Council). It is desirable to set out relevant passages from those decisions. In Swan Hill Corporation, in the context of determining the validity of a local government by-law, Dixon J said at 756:
In considering the validity of any provision adopted in the supposed exercise of a limited power of a legislative nature, the first and often most decisive step is to ascertain the true scope of the measure impugned and the legal effect it would produce.
61 At 755 of Swan Hill Corporation, Rich J reiterated his earlier observations in Footscray Corporation regarding the limited utility of former decisions in construing similar phrases in different legislative provisions (in the context of ascertaining the meaning and scope of the word "regulating" and "restraining"), with which we respectfully agree and apply here:
For my part I think that the interpretation of by-law-making power is not made easier or more certain by the constant recourse to former decisions on powers on very different subjects which happen to contain some of the catch words and phrases belonging to the draftsman's vocabulary. I recognize that the desire to obtain consistency and continuity of decision - a desire highly commendable - naturally leads to an examination of former cases presenting analogies proximate or remote to the problem which happens to be in hand. But sometimes a greater certainty is actually obtained by the more direct course of natural and instinctive interpretation based upon ordinary experience of the use of English terms and due reflection upon the character and implications of the subject matters.
62 Relevant guidance may also be obtained from the following passages in Northern Land Council, which involved a challenge to the validity of a Regulation made by the Administrator of the Northern Territory under the Planning Act 1979 (NT), which had the effect of extending the township of Darwin (with a population then of about 50,000) to cover an area of 4,350 square kilometres thereby rendering that land unavailable to be claimed as unalienated Crown land under s 50(1)(a) of the Aboriginal Land Rights (Northern Territory) Act 1976 (Cth). At 187, after stating that the regulation-making power was to be exercised only for planning purposes, Gibbs CJ added that such a power "does not enable…[the making of] regulations 'which go outside the field of operation which the Act marks out for itself'". His Honour then cited approvingly the following statement of principle in Shanahan v Scott (1957) 96 CLR 245 at 250:
… such a power does not enable the authority by regulations to extend the scope or general operation of the enactment but is strictly ancillary. It will authorise the provision of subsidiary means of carrying into effect what is enacted in the statute itself and will cover what is incidental to the execution of its specific provisions. But such a power will not support attempts to widen the purposes of the Act, to add new and different means of carrying them out or to depart from or vary the plan which the legislature has adopted to attain its ends.
63 Another passage from Northern Land Council is that from the judgment of Stephen J at 204, which is relevant here and, in particular, to the correctness of the primary judge's finding that the Minister's power under s 9A(6) is unfettered:
Where a Parliament confers powers they will seldom if ever be conferred in gross, devoid of purposes or criteria, express or implied, by reference to which they are intended to be exercised.
64 Applying those principles and guidance, we consider that the task of construing s 9A and related provisions in the Act with a view to determining whether the Determination is ultra vires should proceed as follows.
65 First, s 9A(1) effectively creates a rule or proposition that a person who is engaged in an offshore resources activity as defined in s 9A(5) is deemed to be in the migration zone. That rule or proposition operates by reference to the definition of offshore resources activity in s 9A(5). The deeming rule applies except where the Minister has made a relevant determination under s 9A(6). Sections 9A(5)(a) and (b) manifest a clear statement of Parliamentary intention to bring within the regulatory ambit of the Act persons who are engaged in operations and activities carried out under the two specified and existing Commonwealth Acts which regulate a large part of Australia's offshore resources industry. However, the Minister has a power to determine exceptions to that state of affairs. In the case of s 9A(5)(c), which relates to other non-specific legislation of the Commonwealth, a State or a Territory, any activity, operation or undertaking which is carried out under such legislation is captured by the Act only if the Minister so determines. Accordingly, the Minister's power of determination under s 9A(6) operates differently in relation to s 9A(5)(a) and (b) than it does with (c).
66 In our view, particular significance attaches to the fact that the term "except" was deliberately chosen in s 9A(5) in defining "offshore resources activity" by reference to a potentially wide range of operations or activities carried out under the Offshore Petroleum Act or the Offshore Minerals Act except an operation or activity determined by the Minister under s 9A(6). When used in that context, we consider that the term "except" (which appears in s 9A(5)(a) and (b), but not in s 9A(5)(c)) does not denote that the Minister's power of determination can be exercised so as completely to extinguish the items within the relevant category or class in s 9A(5)(a) or (b). Indeed, we consider that the term should be given its ordinary meaning, which is reflected in the following extract from Cockle at 165 per Dixon CJ, McTiernan and Kitto JJ:
An exception assumes a general rule or proposition and specifies a particular case or description of case which would be subsumed under the rule or proposition but which, because it possesses special features or characteristics, is to be excluded from the application of the rule or proposition. It is not a conception that can be defined in the abstract with exactness or applied with precision; it must depend very much upon context.
To similar effect, Williams J in Cockle at 168 said the following about the concept of an "exception" (which applies equally to the verb "except"):
It is a particular thing or things excepted out of the general thing granted.
67 Having regard to these textual matters, we consider that the Minister's power under s 9A(6) to create an exception to the rule cannot be used to eviscerate a substantial part of the rule by denuding s 9A(5)(a) and (b) of any content. That construction is not avoided by the possibility that the Minister might in the future make a determination in relation to s 9A(5)(c) which has the effect of adding a further activity, operation or undertaking to the Act's regulatory scheme. It is evident that, under the 2013 Amending Act, while the Minister was given a power to adjust the particular activities which were captured by the regulatory scheme of the Act by the combined operation of s 9A(1) and (5), it was not intended that the Minister could use that power to restore the position which existed when Allseas was decided.
68 Secondly, the Act and the 2013 Amending Act must be regarded as "one connected and combined statement" of the Parliament: Commissioner of Stamps v Telegraph Investment Co Pty Ltd [1995] HCA 44; (1995) 184 CLR 453 at 479 and s 11B of the Acts Interpretation Act. Section 9A(1) is a deeming provision which identifies what is an offshore resources activity for the purposes of the Act. Similarly, s 41(2B) is a related provision outlining certain visa requirements. If the Determination is valid, ss 9A(1) and 41(2B) would be rendered otiose. The definition and the related provisions were intended to have work to do: Project Blue Sky Inc v Australian Broadcasting Authority [1998] HCA 28; (1998) 194 CLR 355 at [71]. Properly construed, what the text of the statute reflects is that the Parliament intended that, in the case of s 9A(5)(a) and (b), the scope of the definition of "offshore resources activity" was able to be contracted to some extent but that a level of operation or activity should be maintained beyond that which related to the matters described in ss 8 and 9: cf Morton v Union Steamship Co of New Zealand Ltd (1951) 83 CLR 402 at 410. If the Parliament's intention was that the power under s 9A(6) could be used to reverse the definitions in s 9A(5), it might be expected that an expression such as "subject to" would have been used and not the term "except".
69 Thirdly, we do not accept the Minister's submission that there is no relevant "rule" because the way in which the Minister exercises the power conferred by s 9A(6) determines the scope of the "rule" in s 9A(1), with the consequence that the making of a Ministerial determination cannot empty any rule because the rule is inherently susceptible to contraction or expansion depending on the exercise of the Minister's power under s 9A(6). That submission is inconsistent with the text and structure of s 9A as discussed above.
70 Fourthly, we consider that the construction set out above conforms with and promotes the purpose and object of the 2013 Amending Act (see s 15AA of the Acts Interpretation Act). As directed by the High Court in CIC Insurance at 408, the modern approach to statutory interpretation insists that context be considered at the outset and not merely when ambiguity might be thought to arise. Moreover, context includes the mischief which the relevant provisions were intended to remedy and reference can be made to documents such as the Explanatory Memorandum to the 2013 Amending Bill with a view to ascertaining that purpose or mischief.
71 The purpose or mischief to which the 2013 Amending Act was directed is apparent in the following passages from the Explanatory Memorandum which, although lengthy, are important to the proper construction of s 9A and s 41(2B) and (2C):
OUTLINE
…
The Government is committed to maintaining the security of Australia's borders.
Under the current legislative framework, the Government has an incomplete picture of the number of foreign workers in the offshore maritime zone. This is in part due to the absence of a regulated visa regime to capture those engaged in Australia's offshore maritime zones and the corresponding migration information. There are security ramifications as a result of the inability to regulate foreign workers engaged in offshore resources activities in an immigration context. The June 2012 Report of the Offshore Oil and Gas Resources Sector Security Inquiry recognised that visa security checks are one of the only ways Australia is able to examine non-citizen workers in this security-sensitive industry.
The exploration and exploitation of the natural resources in Australia's offshore maritime zones contributes significantly to the Australian economy and employs thousands of Australian workers. The inability for the Government to regulate foreign workers in Australia's offshore resources industry undermines the integrity of Australia's migration program and visa regime regulating work entitlements. As a result, there is a risk that foreign workers undertaking activities involved in the exploration and exploitation of Australia's natural resources and who therefore form part of the Australian employment sector may be working under conditions and receiving wages that do not adhere to Australian standards. This reduces work opportunities for Australian citizens and non-citizens who hold relevant visas permitting work and also puts businesses that only engage workers who hold valid visas to work at a competitive disadvantage.
The amendments in this Bill will regulate foreign workers participating in offshore resources activities by bringing these persons into the migration zone and thereby requiring them to hold a visa under the Act. In terms of selecting offshore resources activities, the Taskforce recommended referencing a legislative solution that comprehensively administer the activities of the offshore resources industry comprising the Offshore Petroleum and Greenhouse Gas Storage Act 2006 (the Offshore Petroleum Act) and the Offshore Minerals Act 1994 (the Offshore Minerals Act). In addition to these two Acts, the Bill will create a power for the Minister to make a determination in writing for the purposes of defining offshore resources activity. This will provide the Minister with flexibility to declare certain activities administered by other regulatory schemes as offshore resource activities for the purposes of the new deemed migration zone. This would include projects that take place in areas that are within the coastal waters of the States and the Northern Territory which are regulated under State and Territory laws rather than their Commonwealth equivalents.
The legislative measures will supplement the current framework under the Act which defines, as part of the migration zone, Australian resources installations and Australian sea installations. Together with the existing provisions in the Act, this new comprehensive framework will ensure that workers in Australia's offshore resources industry are regulated under the Act and required to hold specific visas. Individuals who engage in offshore resources activities in Australia's offshore maritime zones will be subject to existing compliance measures in the Act which address breaches of work and visa conditions.
…
SCHEDULE 1 - Amendments
Part 1 - Amendments
Migration Act 1958
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Item 6 After section 9
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38. New section 9A creates a new framework that provides that persons in an area participating in, or supporting, an offshore resources activity are taken to be in the migration zone (the deeming provision). New section 9A further clarifies how this new framework operates by deeming when persons are taken to be in Australia, taken to travel to Australia, taken to enter Australia and or taken to leave Australia. It further defines offshore resources activity for the purposes of the Act. The purpose of this amendment is to bring persons participating in, or supporting, an offshore resources activity in the relevant area within the ambit of the Act, thereby requiring these persons to hold visas.
…
41. New section 9A is based on the recommendations of the Taskforce. The Taskforce recommended that the existing legislative framework that essentially provides that persons are in the migration zone based on where they are physically located be supplemented with a new legislative concept. The policy intention is to provide that all offshore resource workers, including support staff, are taken to be in the migration zone when they are engaged to conduct activities regulated by Commonwealth, State and Territory legislation relating to the exploration and exploitation of Australia's natural resources.
…
48. New subsection 9A(1) operates as the new deeming provision and supplements the current definition of the migration zone in subsection 5(1) for the purposes of offshore resources activities. However, it does not modify the existing definition of the migration zone in subsection 5(1).
49. The purpose of this amendment is to require persons participating in, or supporting, an offshore resources activity in a relevant area to hold visas to work. Current subsection 5(23) provides that to avoid doubt, in this Act is taken, when followed by the infinitive form of a verb, has the same force and effect as is deemed when followed by the infinitive form of that verb. New subsection 9A(1) therefore operates as a deeming provision.
50. New subsection 9A(1) does not define what "an area" is and has been left deliberately broad. Instead, it is intended for the relevant area to be read in conjunction with the definition of offshore resources activity in new subsection 9A(5). New subsection 9A(5) refers to certain operations or activities under the Offshore Petroleum Act, Offshore Minerals Act or a law of the Commonwealth, a State or a Territory determined by the Minister. Those Acts themselves will define the area (for example, a licence under the Offshore Minerals Act will define a particular area in which the regulated operation may take place).
Meaning of offshore resources activity
Subsection 9A(5)
…
90. New subsection 9A(5) is not intended to modify the existing framework created by these Acts relating to offshore resources activities, and define new activities, but rather link to existing activities. When selecting the activities associated with the exploration and exploitation of Australia's natural resources, the Taskforce recognised that there is already a regime which comprehensively covers the activities of the offshore resources industry. The Taskforce concluded that linking the Act to the current regulatory schemes under the Offshore Petroleum Act, the Offshore Minerals Act and related State and Territory legislation, would ensure that the Migration Act covers the same activities being conducted under existing legislation regulating the offshore resources industry.
…
92. New paragraphs 9A(5)(a) and 9A(5)(b) make it clear that all regulated operations under the Offshore Petroleum Act and all activities performed under a licence or a special purpose consent under the Offshore Minerals Act are captured by the definition of offshore resources activity unless the Minister has excluded the operation or activity by using his powers under subsection 9A(6). This would allow the Minister to exclude from the Act activities defined under the Offshore Petroleum Act and the Offshore Minerals Act which the Minister considers unsuitable to be captured by the definition of offshore resources activity.
…
94. New subparagraph 9A(5)(c)(ii) provides that an offshore resources activity can also include an activity, operation or undertaking (however described) that is being carried out, or is to be carried out under a law of the Commonwealth, a State or a Territory determined by the Minister under subsection 9A(6).
95. The purpose of this amendment is to enable the Minister to determine as an offshore resources activity, an activity which is not covered by the Offshore Petroleum Act or the Offshore Minerals Act under new subsection 9A(6) for the purposes the deeming provision in new subsection 9A(1). Therefore, a person who is carrying out an activity under legislation that the Minister has determined to be an offshore resources activity would be taken to be in the migration zone because they are participating in an offshore resources activity.
96. This provision recognises and accounts for changes in the offshore resources sector and possible advances in technology. It recognises that additional laws may be developed in the future to govern new offshore resource activities that may emerge.
…
Subsection 9A(6)
99. New subsection 9A(6) provides that the Minister may, in writing, make a determination for the purposes of the definition of offshore resources activity in subsection 9A(5).
100. More specifically, this amendment provides the Minister with the power to make determinations with respect to the definition of offshore resources activity by:
• exempting certain regulated operations under the Offshore Petroleum Act from the definition of offshore resources activity;
• exempting certain activities performed under a licence or a special purpose consent under the Offshore Minerals Act from the definition of offshore resources activity;
• capturing certain activities, operations or undertakings carried out, or to be carried, out under a law of the Commonwealth, a State or a Territory;
• determining the specific law of the Commonwealth, State or a Territory in which those activities are carried out under; and/or
• limiting the area in which those activities are carried out under.
101. The purpose of this amendment is to provide the Minister with the flexibility and ability to exempt certain activities administered by the Offshore Petroleum Act and the Offshore Minerals Act from the definition of offshore resources activity. Further, this amendment will provide the Minister with the ability to capture certain other activities not administered by these two Acts but administered by a law of the Commonwealth, a State or a Territory.
102. This amendment will also provide the Minister with an additional tool to ensure that any future emergency can be effectively dealt with and to exclude any unintended consequences which may breach Australia's international obligations.
…
Subsection 9A(7)
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105. A legislative instrument is to be utilised as the Minister would need flexibility to make determinations for the purpose of the definition of offshore resources activity and these instruments would need to be revised frequently, in consultation with stakeholders.
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Item 8 After subsection 41(2A)
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Subsections 41(2B) and 41(2C)
123. New subsection 41(2B) provides that in addition to any restrictions applying because of Regulations made for the purposes of paragraph 41(2)(b), a condition of a visa that allows the holder of the visa to work is not taken to allow the holder to participate in, or support, an offshore resources activity in relation to any area unless the visa is:
• a permanent visa;
• or a visa prescribed by the regulations for the purposes of this subsection.
124. The purpose of this amendment is to ensure that all non-citizens engaged in an offshore resources activity hold a visa or a permanent visa to participate in, or support, the relevant activity.
125. A person who is not the holder of a permanent visa or a visa prescribed by the Regulations for the purposes of new subsection 41(2B) could not lawfully participate in, or support, an offshore resources activity.
…
128. New subsection 41(2C) provides that to avoid doubt, for the purposes of subsection 41(2B), a person may participate in, or support, an offshore resources activity in relation to an area whether the person:
• is on an Australian resources installation in the area;
• or is, under section 9A, otherwise in the area to participate in, or support, the activity.
129. This new subsection mirrors new subsection 9A(8) which is inserted by item 6 above. The purpose of this amendment is to put beyond doubt that persons engaged in any type of offshore resources activity in the relevant area will be required to hold a permanent visa; or a visa prescribed by the Regulations to participate or support that activity. This will be the case regardless of whether the person is engaged in an activity on an Australian resources installation and is already taken to be in the migration zone under the Act or is participating in or supporting an offshore resources activity for the purposes of new section 9A and will therefore be taken to be in the migration zone under new subsection 9A(1).
130. The policy intention behind new subsections 41(2B) and 41(2C) is to enable the Department to identify the number of non-citizens working in the offshore resources sector and information about the work they are doing. Without a specific visa for this work, this will not be possible. Identification of the number of non-citizens working in the sector enables identification of training needs for Australian workers. The Taskforce also received feedback that the current visa products available are not suitable for the needs of industry, for example, where there is a need to transfer a worker from one offshore project overseas to a project in Australian waters at short notice. The new visa product would provide flexibility for industry and would enable the Department to identify the number of non-citizens working in the sector.
…
(Emphasis in original.)
72 Those passages indicate the following matters concerning the purpose of the relevant amendments:
(a) the 2013 Amending Act was intended to introduce a new concept into the Act, by deeming a person to be in the migration zone where the person was involved in "offshore resources activity" as defined in s 9A(5);
(b) an express purpose of the amendments, driven in part by border security considerations, was to regulate foreign workers participating in offshore resources activities by bringing these persons into the migration zone and thereby requiring them to hold a specified visa under the Act;
(c) the amendments introduced by the 2013 Amending Act were intended to supplement and expand the previous framework under the Act which defined the migration zone by reference to "Australian resources installations" and "Australia sea installations"; and
(d) the Minister was empowered to make a legislative determination in writing for the purposes of defining "offshore resources activity" to provide the Minister with flexibility to:
(i) exempt from that definition certain operations or activities carried out under the Offshore Petroleum Act or the Offshore Minerals Act where, for example, the Minister considered them to be unsuitable to be included within the definition and, therefore, subject to regulation under the Act; and
(ii) capture certain other activities, operations or undertakings administered by regulatory schemes other than the Offshore Petroleum Act and the Offshore Minerals Act as determined by the Minister.
73 These extracts from the Explanatory Memorandum support the textual construction of s 9A(6) in [65]-[67] above. In particular, the Explanatory Memorandum makes it clear that the primary purpose of the amendments was to have the Act apply to foreign workers who are engaged in offshore resource activities or operations, by requiring them to hold specified visas. Recognising, however, that there may need to be some particular exceptions or exemptions from such regulation, the Minister was empowered to make a determination to that effect. The Parliament's intention was to confer upon the Minister a power to except or exempt particular activities or operations carried out under the Offshore Petroleum Act or Offshore Minerals Act, not to reverse the Parliament's desire and intention to bring within the Act non-citizens who are engaged in operations and activities under the Offshore Petroleum Act or the Offshore Minerals Act.
74 Fifthly, the textual and contextual reasons for construing the relevant provisions in the manner indicated above is further reinforced in our view by consideration of the relationship between the Executive and Legislative branches of government. It is not readily to be supposed that a legislative provision giving the Executive power to modify the reach of a statutory provision (by creating exceptions) should be understood as permitting the de facto repeal of the only part of the provision which supplied an immediate and substantive content to the new concept of "offshore resources activity" (i.e. in s 9A(5)(a) and (b)). We respectfully agree with the following statement by Weinberg J in Vanstone at [101]:
Pearce [Pearce and Argument, Delegated Legislation in Australia, Butterworths, 2nd Edition (1999)] suggests that the doctrine of separation of powers limits the scope of delegated legislation in two ways. First, it is not permissible for legislation to be made by a body other than the parliament without the authority of the parliament. Second, while the parliament may empower another body to alter the effect of an Act, that power will be strictly construed. The delegate will not be permitted to destroy the purpose of the empowering Act: State of New South Wales v Law (1992) 29 ALD 215.
75 We are not persuaded by the Minister's submission that the primary judge's construction should be affirmed because of the difficulties of precisely identifying the boundaries of the Minister's power under s 9A(6) including, for example, identifying the threshold at which the exercise of the power would tip from being valid to invalid. The validity of any other determination purportedly made under s 9A(6) will necessarily fall to be determined having regard to all the relevant circumstances and will be guided by the general principle that the power is limited by the subject matter, scope and purpose of the relevant legislative provisions. An abstract bright line which demarcates the boundary between validity and invalidity in this context cannot be drawn. But the same is true of other settings where the question arises as to whether the exercise of a power to make subordinate legislation is authorised by the enabling Act. The point is well illustrated by the long series of cases which have grappled with the question whether a power to regulate includes a power to prohibit (see the many cases on this topic referred to in Pearce and Argument, Delegated Legislation in Australia, Butterworths, 3rd Edition (2005) at [15.3]-[15.14]). Difficulties of construction relating to hypothetical future determinations under s 9A(6) should not stand in the way of determining whether the Determination is ultra vires.
76 Nor do we accept the Minister's separate submission, which was emphasised in oral address, that the effect of the 2013 Amending Act merely operates at the "margins" of the definition of the "migration zone" in s 5 of the Act. As is evident from both the terms of s 9A and the relevant parts of the Explanatory Memorandum set out above, effect was given to the intention that, prima facie, all regulated operations and activities under the Offshore Petroleum Act and Offshore Minerals Act would be regulated under the Act, not by amending the definition of "migration zone" in s 5, but by linking the existing regulatory framework under the Act to the wide range of operations and activities carried out under these other two Commonwealth Acts (together with, potentially, operations, activities and undertakings carried out under related Commonwealth, State or Territory legislation as determined by the Minister). A wide range of activities and operations relating to offshore petroleum and mineral resources are regulated by these two Commonwealth Acts through an array of permits, leases, licences and authorities. The activities regulated under these Acts are broader than those which are captured by the definitions of "Australian resources installation" and "Australian sea installation" in ss 8 and 9 (which are picked up in the definition of "migration zone" in s 5). As confirmed by the Explanatory Memorandum, the new concept of "offshore resources activity", as defined in s 9A(5), provided a "comprehensive framework" which, together with the then existing framework, would ensure that foreign workers in Australia's offshore resources industry would be required to hold specific visas. It is an understatement to describe the effect of the amendments as merely "marginal".
77 Sections 41(2B) and (2C) also demonstrate that the amendments were not merely marginal in character. These provisions have an important substantive effect. In the case of s 41(2B), a person who is engaged in an offshore resources activity as defined must hold either a permanent visa or a visa prescribed by the regulations for the purposes of the provision. Consequently, a person who is engaged in an offshore resources activity who does not hold a permanent visa or a prescribed visa could not lawfully participate in, or support, an offshore resources activity. And, to avoid doubt, s 41(2C) provides that, for the purposes of s 41(2B), a person may engage in an offshore resources activity in relation to an area whether the person is on an Australian resources installation in the area (as defined in s 5) or is, under s 9A, otherwise in the area to participate in, or support, such an activity. Accordingly, any person engaged in any type of offshore resources activity in the relevant area is required to hold a permanent visa or a visa prescribed by the regulations to participate or support that activity, regardless of whether the person is already taken to be in the migration zone because he or she is on an Australian resources installation or is participating in, or supporting, an offshore resources activity under the new s 9A.