Held, claims dismissed on those grounds for which permission to proceed was granted. (1) In so far as sections 87(3)(b), 94(8) and 106(1)(b) of the Planning Act 2008 Act entitled the examining authority and Secretary of State respectively, when considering a development consent order, to disregard representations which related to the merits of policy set out in a national policy statement, the Airports National Policy Statement had established three matters of national policy which could not be challenged in any future development consent order process, namely that (i) there was a pressing national need for new airport capacity in the south east of England, (ii) that need was to be met by the NWR scheme as the scheme preferred by the Government and not by any of the alternatives considered, and (iii) the assessments which an applicant for a development consent order would have to carry out, and the planning tests that it would have to meet in order for an order to be granted, were as set out in the statement. Consideration of the comparative merits of an alternative scheme which the policy in the statement had rejected was therefore precluded in any future development consent order process. That exclusion would apply even where an objector sought to rely on a change in the circumstances on which the policy decision was based. Significant changes in circumstance affecting the basis for a policy in a national policy statement were to be taken into account only through the statutory process of review by the Secretary of State, pursuant to section 6, if, after assessment, he considered that the policy would have been materially different had that change been anticipated at the time when the statement was first published. However, while section 104(3) required an application for a development consent order to be decided in accordance with any relevant national policy statement, section 104(7) of the 2008 Act created an exception to the extent that the Secretary of State was satisfied that the adverse impact of a proposed development would outweigh its benefit. That left open the possibility of making of an objection in the development consent order process that a change in circumstance since the designation of a national policy statement had affected the assessment of the adverse impacts of the proposed development itself, and thus might cause the balance struck under section 104(7) to come down against the granting of development consent (paras 100, 106–110).

(2) Section 5(7) of the 2008 Act, requiring a national policy statement to “give reasons for the policy set out in the statement”, required that the statement contain the rationale for the policy but did not require the reasons to be comprehensive or that every reason and consideration that the policy-maker had in mind when promoting or designating the statement be set out. Since section 5(7) did not concern the giving of reasons for a specific decision, but rather reasons for the policy set out in the statement, the well-established approach to the statutory requirements for the structure and content of development plans was instructive. It was for the Secretary of State to make judgments about what matters to include in the statement, and to what level of detail, and what material used to support those policies should be set out in other documents accompanying the draft statement published for consultation. In such a complex area as aviation infrastructure policy, it would be impractical to include in the statement, whether a draft or as finally designated, every matter relied on by the policy maker as a reason for his policy. Further, section 5(7) did not impose any obligation on the Secretary of State to give reasons responding to points raised in consultation, since the reasons to be given were the reasons for proposing the policy and thus, by definition, could not be the Secretary of State’s reasoning in response to representations made about the proposal in the consultation exercise. Accordingly, it was unnecessary for the Secretary of State to give reasons for rejecting every point made in response to consultation, any duty to give reasons being confined to the common law requirements for consultation. It followed that the reasons included in the national policy statement pursuant to section 5(7) were not to be regarded as an exhaustive statement of all the reasoning which underpinned the policies set out in the statement and a claimant could not rely upon the mere fact that a matter had not been mentioned in the reasons stated in the statement itself to demonstrate that the Secretary of State had left a material consideration out of account (paras 116–123).

(3) Section 7(2) conferred a broad discretion on the Secretary of State with regard to the carrying out of consultation on a national policy statement, subject to compliance with established principles of fairness. Where a broad consultation exercise was carried out to ensure participation in the Secretary of State’s decision-making process and to promote better decision-making in the formulation of a national policy, the Secretary of State was entitled to consider the whole range of responses made to him and then to form his own conclusions independently of the views of any section of consultees, without being obliged to consult on, or consider and respond to, every item of detail (paras 124–127, 131, 134, 137).

(4) The appropriate degree of scrutiny on judicial review depended on the nature of the decision under challenge, the nature of any right or interest which it sought to protect, the process by which the decision under challenge was reached and the nature of the ground of challenge. The nature of the policy decisions brought together in a document such as the Airports National Policy Statement covered a wide spectrum which affected the intensity of review. First, in so far as Parliament had scrutinised and approved the content of the Airports National Policy Statement as later designated, “considerable caution” was to be applied when reviewing matters which had been specifically addressed in the parliamentary process and had formed part of an overall judgment balancing those considerations against the national economic interest. Second, while some grounds of challenge might may be of a hard-edged nature, the legal merits of which were not affected by the fact that the statement dealt with policy making on a wide spectrum, others might relate to subjects which formed part of a mix of considerations in the development of policy in the statement, and it might be helpful to consider where the target of the challenge lay on the policy “spectrum”, which might go to the question, not only whether an error has been made, but whether a material error of law had occurred. Third, if a ground of challenge was made out and the question of relief was being considered, it might assist the court to consider where the legal error sat in relation to that policy spectrum, the statement and public interest considerations viewed as a whole. In so far as the claimants raised issues relating to climate change and challenged the principle of whether a substantial increase in airport capacity should be promoted, that was a policy issue for the Government and Parliament to address at a high strategic level, which engaged the widest possible range of economic and social considerations and involved striking a balancing between the protection of the environment against harm caused by airport expansion, requiring political judgment as to what was in the overall public interest. However, the main grounds of challenge did not generally raise issues in respect of which parliamentary approval was an especially weighty matter in relation to the appropriate degree of scrutiny, in particular so far as legal errors were alleged in implementing the requirements of the statutory framework. In so far as the claimants advanced irrationality challenges, or challenges to what were essentially matters of judgment, a heavy onus was placed on them and a margin of appreciation was to be allowed to the Secretary of State. In relation to grounds of challenge which related to matters of technical judgment and expertise, it was not the role of the court, in judicial review proceedings, to resolve conflicts of expert opinion, particularly not in favour of a claimant on whom the burden of proof lay, and the court would accord an enhanced margin of appreciation to decisions involving or based upon “scientific, technical and predictive assessments” by those with appropriate expertise. That margin was substantial in relation to matters of technical judgment and expertise, modelling and predictive assessments made by independent expert bodies assigned to make such assessments on the basis of expert evidence. In particular, the Secretary of State had been entitled to attach great weight to the reports of the Airports Commission as an independent and expert body, comprising a panel of independent experts, which had been specifically instructed to examine the extent to which there was a need for additional airport capacity, and, if so, how that need should be met (paras 146, 151–152, 161, 166–173, 179–184).

(5) The Secretary of State’s rejection of proposals for a second runway at Gatwick airport as an alternative to the NWR scheme, for the purposes of articles 6(3) and 6(4) of Council Directive 92/43/EEC, on the ground that it failed to meet the objective of maintaining the United Kingdom's hub status, did not involve any illegality in circumstances where the Secretary of State was to be given a significant margin of appreciation in that regard and the evidence was firmly against the Gatwick scheme being able to maintain the UK’s hub status (paras 353, 356, 361, 371, 667–668).

(6) The information in article 5(1) of and Annex I to Directive 2001/42/EC which was to be included in an environmental report was, by article 5(2), that which “may reasonably be required”, which required a judgment on the part of the authority responsible for preparing the plan or programme and was a matter for the evaluative assessment of the authority subject only to review on normal public law principles including reasonableness. Where an authority failed to give any consideration at all to a matter which it was explicitly required by the Directive to address, such as whether there were reasonable alternatives to the proposed policy, the court might conclude that there had been non-compliance. Otherwise, decisions on the inclusion or non-inclusion in the environmental report of information on a particular subject, or the nature or level of detail of that information, or the nature or extent of the analysis carried out, were matters of judgment for the plan-making authority which could only be challenged on the grounds of irrationality. Applying that test, the Secretary of State had not breached article 5(1) and (2) of Directive 2001/42 in the manner alleged by the claimants (paras 433–434, 449, 487, 500–502, 667–668).

(7) On the issue whether the Secretary of State had approached the consultation with a closed mind, a distinction was to be made between predetermination, which was unlawful, and predisposition, which was not. A policy-maker did not have to be, and usually was not, detached or disinterested as between the possible policy option and it might be difficult, if not impossible, for a Secretary of State discharging his policy-making functions under the 2008 Act to avoid having a predisposition in favour of the policies he proposed. Given the role of a policy-maker in a statutory scheme such as the 2008 Act, neither actual predetermination, nor apparent predetermination in the sense of a real risk of the Secretary of State having proceeded with a closed mind, was easy to prove and, in particular, when the court was faced with an allegation of predetermination in that context, it needed to be cautious about the inferences which could properly be drawn from statements and conduct on the part of the policy-maker. The consultation process under section 7 of the 2008 Act was concerned not with the ultimate decision of whether a specific project should be approved by the grant of development consent but instead with representations on a policy which, by definition, the Secretary of State had already provisionally decided should appropriately be designated. The legislation proceeded on the basis that he would already have reached that stage by the time the consultation process under section 7 began. Taking those considerations into account, the evidence did not disclose either a closed mind or a real risk of a closed mind on the part of the Secretary of State (paras 509–511, 519, 538, 540, 544, 546–549, 551–552, 667–668).