Article 9(2) of the Aarhus Convention, replicated in the PP Directive, says:
“2. Each Party shall, within the framework of its national legislation, ensure that members of the public concerned
(a) Having a sufficient interest or, alternatively,
(b) Maintaining impairment of a right, where the administrative procedural law of a Party requires this as a precondition, have access to a review procedure before a court of law and/or another independent and impartial body established by law, to challenge the substantive and procedural legality of any decision, act or omission subject to the provisions of article 6 and, where so provided for under national law and without prejudice to paragraph 3 below, of other relevant provisions of this Convention.
What constitutes a sufficient interest and impairment of a right shall be determined in accordance with the requirements of national law and consistently with the objective of giving the public concerned wide access to justice within the scope of this Convention. To this end, the interest of any non-governmental organization meeting the requirements referred to in article 2, paragraph 5, shall be deemed sufficient for the purpose of subparagraph (a) above. Such organizations shall also be deemed to have rights capable of being impaired for the purpose of subparagraph (b) above. The provisions of this paragraph 2 shall not exclude the possibility of a preliminary review procedure before an administrative authority and shall not affect the requirement of exhaustion of administrative review procedures prior to recourse to judicial review procedures, where such a requirement exists under national law.”
There are six cases on standing in the context of Aarhus:
First, Case C-427/07 Commission of the European Communities v Ireland  E.C.R. I-6277;  Env. L.R. 8 the Commission argued that criterion of “substantial interest” required for seeking judicial review was also submitted to be stricter than that of “sufficient interest” in the PP Directive. At para. 82 the CJEU stated:
“… Member States must ensure that, in accordance with the relevant national legal system, members of the public concerned having a sufficient interest, or alternatively, maintaining the impairment of a right, where the administrative procedural law of a Member State requires this as a precondition, have access to a review procedure under the conditions specified in those provisions, and must determine what constitutes a sufficient interest and impairment of a right consistently with the objective of giving the public concerned wide access to justice.”
At para. 83, the CJEU noted that Ireland had adopted provisions under which the right of access to justice in this area “depends directly” on the applicants’ interest. At para. 84, the Court stated:
“… there is no need to ascertain whether the criterion of substantial interest as applied and interpreted by the Irish courts corresponds to the sufficient interest referred to in Directive 2003/35 [which inserted article 10a into Directive 85/337 ] as that would lead to calling into question the quality of the transposition having regard, in particular, to the competence of the Member States recognised by that directive to determine what constitutes a sufficient interest consistently with the objective which that directive pursues.”
Under Irish law, the applicant must prove a peculiar and personal interest of significant weight which is affected by or connected with the development in question (Harding v Cork County Council  IECS 27). When considering that test, Kokott A.G. stated:
“66. Under Directive 2003/35 , that is to say under the first sentence of the third paragraph of art.10a of the EIA Directive and the first sentence of the third paragraph of art.15a of Directive 96/61 , the Member States are to determine what constitutes a sufficient interest and impairment of a right. This is admittedly to be done consistently with the objective of giving the public concerned wide access to justice. However, an even more restrictive access rule is also possible, namely the requirement to maintain the impairment of a right. The directive thus leaves it to the Member States to define “sufficient interest”, without laying down any mandatory minimum standard.
69. However, in order to determine what constitutes sufficient interest to bring an action, a balance must necessarily be struck. Effective enforcement of the law militates in favour of wide access to the courts. On the other hand, it is possible that many court actions are unnecessary because the law has not been infringed. Unnecessary actions not only burden the courts, but also in some cases adversely affect projects, whose implementation can be delayed. Factors such as an increasing amount of legislation or a growing litigiousness of citizens, but also a change in environmental conditions, can affect the outcome of that balancing exercise. Accordingly, it cannot be automatically inferred from more generous access to the courts that was previously available that a more restrictive approach would be incompatible with the objective of wide access.”
The Court found Irish law to be compatible with the PP Directive on the issue of standing though there were findings against Ireland on other grounds – see above.
Second, Case C-263/08 Djurgarden-Lilla Vartans Miljoskyddsforening v Stockholms Kommun genom dess Marknamnd  E.C.R. I-9967 (”the Stockholm case”).
The PP Directive, like the Aarhus Convention, provides that provides that non-governmental organisations promoting environmental protection and meeting any requirements under national law shall be deemed to have an interest sufficient to give them standing to bring an environmental challenge.
The Municipality of Stockholm concluded a contract with a private company to construct a tunnel through the hills in Northern Djurgården to house electricity cable. The Environmental Chamber of the District Court of Stockholm (miljödomstolen vid Stockholms tingsrätt ) granted development consent to carry out the works. The Djurgården environmental association (Djurgården-Lilla Värtans Miljöskyddsförening) sought to appeal against that decision, but the action was held to be inadmissible, on the basis that it did not fulfil the condition set down in the relevant national law, which required an environmental association to have 2,000 members to be entitled to appeal. The Djurgården environmental association appealed and a reference was made to the CJEU, asking inter alia, (i) whether Art. 10a of the EIA Directive implied that members of the public concerned were to have access to a review procedure to challenge a granting of development consent even where they had had an opportunity to participate in the decision-making procedure; and (ii) whether Member States were permitted, under the Directive, to allow small local environmental associations to participate in the decision-making procedure but to have no right of access to a review procedure to challenge the decision subsequently taken. The CJEU held that ”members of the public concerned, within the meaning of art.1(2) and 10a of Directive 85/337 , must be able to have access to a review procedure to challenge the decision by which a body attached to a court of law of a Member State has given a ruling on a request for development consent, regardless of the role they might have played in the examination of that request by taking part in the procedure before that body and by expressing their views” (para. 39) and that the EIA Directive ”precludes a provision of national law which reserves the right to bring an appeal against a decision on projects which fall within the scope of that directive solely to environmental protection associations which have at least 2,000 members” (para. 52). The CJEU said:
”44 As regards non-governmental organisations which promote environmental protection, art.1(2) of Directive 85/337 , read in conjunction with art.10a thereof, requires that those organisations “meeting any requirements under national law” are to be regarded either as having “sufficient interest” or as having a right which is capable of being impaired by projects falling within the scope of that directive.
45 While it is true that art.10a of Directive 85/337 , by its reference to art.1(2) thereof, leaves to national legislatures the task of determining the conditions which may be required in order for a non-governmental organisation which promotes environmental protection to have a right of appeal under the conditions set out above, the national rules thus established must, first, ensure “wide access to justice” and, secondly, render effective the provisions of Directive 85/337 on judicial remedies. Accordingly, those national rules must not be liable to nullify Community provisions which provide that parties who have a sufficient interest to challenge a project and those whose rights it impairs, which include environmental protection associations, are to be entitled to bring actions before the competent courts.
46 From that point of view, a national law may require that such an association, which intends to challenge a project covered by Directive 85/337 through legal proceedings, has as its object the protection of nature and the environment.
47 Furthermore, it is conceivable that the condition that an environmental protection association must have a minimum number of members may be relevant in order to ensure that it does in fact exist and that it is active. However, the number of members required cannot be fixed by national law at such a level that it runs counter to the objectives of Directive 85/337 and in particular the objective of facilitating judicial review of projects which fall within its scope.
48 In that connection, it must be stated that, although Directive 85/337 provides that members of the public concerned who have a sufficient interest in challenging projects or have rights which may be impaired by projects are to have the right to challenge the decision which authorises it, that directive in no way permits access to review procedures to be limited on the ground that the persons concerned have already been able to express their views in the participatory phase of the decision-making procedure established by art.6(4) thereof.
49 Thus, the fact relied on by the Kingdom of Sweden, that the national rules offer extensive opportunities to participate at an early stage in the procedure in drawing up the decision relating to a project is no justification for the fact that judicial remedies against the decision adopted at the end of that procedure are available only under very restrictive conditions.
50 Furthermore, Directive 85/337 does not exclusively concern projects on a regional or national scale, but also projects more limited in size which locally based associations are better placed to deal with. As the Advocate General notes, in point 78 of her Opinion, the rule of the Swedish legislation at issue is such as to deprive local associations of any judicial remedy.
51 The Swedish Government, which acknowledges that at present only two associations have at least 2,000 members and thereby satisfy the condition laid down in para.13 of Ch.16 of the Environment Act, has in fact submitted that local associations could contact one of those two associations and ask them to bring an appeal. However, that possibility in itself is not capable of satisfying the requirements of Directive 85/337 as, first, the associations entitled to bring an appeal might not have the same interest in projects of limited size and, secondly, they would be likely to receive numerous requests of that kind which would have to be dealt with selectively on the basis of criteria which would not be subject to review. Finally, such a system would give rise, by its very nature, to a filtering of appeals directly contrary to the spirit of the directive which, as stated in para.33 of this judgment, is intended to implement the Aarhus Convention.”
Third, in Ashton v Secretary of State for Communities and Local Government and Coin Street Community Builders Ltd  1 P. & C.R. 5 the appellant was a local resident whose property was affected by the development. He was a member of the Waterloo Community Development Group (“WCDG”). He did not make any representations to the local authority or at the public inquiry. He stated that he had asked WCDG to make representations on his behalf. The Court of Appeal rejected his s. 288 challenge on the merits but went on to consider whether he would in any event have been a “person aggrieved”. Pill LJ in his judgment considered Article 10a of the EIA Directive, the Stockholm case and Commission v Ireland. He concluded:
“53 The following principles may be extracted from the authorities and applied when considering whether a person is aggrieved within the meaning of s.288 of the 1990 Act:
1. Wide access to the courts is required under s.288 (art.10a , N’Jie).
2. Normally, participation in the planning process which led to the decision sought to be challenged is required. What is sufficient participation will depend on the opportunities available and the steps taken (Eco-Energy , Lardner ).
3. There may be situations in which failure to participate is not a bar (Cumming, cited in Lardner).
4. A further factor to be considered is the nature and weight of the person’s substantive interest and the extent to which it is prejudiced (N’Jie and Lardner). The sufficiency of the interest must be considered (art.10a).
5. This factor is to be assessed objectively. There is a difference between feeling aggrieved and being aggrieved (Lardner).
6. What might otherwise be a sufficient interest may not be sufficient if acquired for the purpose of establishing a status under s.288 (Morbaine).
7. The participation factor and the interest factor may be interrelated in that it may not be possible to assess the extent of the person’s interest if he has not participated in the planning procedures (Lardner).
8. While recognising the need for wide access to the courts, weight may be given, when assessing the prior participation required, and the interests relied on, to the public interest in the implementation of projects and the delay involved in judicial proceedings (A.G. Kokott in Ireland).
54 I do not consider that the appellant had standing under s.288 to bring the present claim. His participation in the planning process was insufficient in the circumstances to acquire standing. He was not an objector to the proposal in any formal sense and did not make representations, either oral or written, at the properly constituted Public Inquiry. Mere attendance at parts of the hearing and membership of WCDG, which has not brought proceedings in this court, were insufficient. I agree with the judge’s conclusion set out at  above.
55 Moreover, the absence of representations before or at the Inquiry about the loss of amenity at his property, either personally or by WCDG, deprived CSCB and the local planning authority of the opportunity to test the extent of the alleged loss and to call evidence in response. That being so, the Inspector, the fact-finding tribunal, was not in a position to assess the extent of the loss and whether it amounts to a sufficient interest. This Court cannot make good that deficiency.
56 I make no finding as to whether the appellant would also fail under the interest limb of the test, though it appears to me likely that he would do so. A major project, approved following proper public consultation and a Public Inquiry, should not readily be challengeable on this or other grounds on the basis of a grievance about amenity such as the appellant’s appears to be. What is a sufficient interest will always be a question of fact and degree. That reinforces the need to place the facts relied on before the decision maker during the planning process.”
Fourth, R (Coedbach Action Team Ltd) v. Secretary of State for Energy and Climate Change  EWHC 2312 (upheld on appeal:  EWCA Civ 1494). Coedbach applied for a PCO in respect of its application for judicial review of a consent for a biomass fuelled power station granted by the Secretary of State. Coedbach was a limited company formed by local residents as a response to a proposal to build two biomass power stations in Wales which Coedbach was opposing. There were ongoing appeals in respect of those proposals. Meanwhile the Secretary of State granted consent under the Electricity Act 1989 for a biomass power station in England and directed that planning permission be deemed to be granted under the Town and Country Planning Act 1990 s. 90(2). Coedbach did not object to the applications for consent and played no part in the process until it issued an application for permission to apply for judicial review of that decision out of a concern that the decision might influence the decisions in respect of the Welsh proposals. The issue of standing arose in the context of the PCO application, and Coedbach’s attempt to rely on the Aarhus Convention:
“29 I accept the submissions made on behalf of the defendant and Interested Party that the claimant is not a member of the public concerned and it is not a person having a sufficient interest. The claimant is a limited company whose aims and objects are made clear, unequivocally, in its Memorandum of Association. Its aim is to protect a particular local environment. The claimant played no part in the decision-making process leading to the grant of the consents to the Interested Party. But for the coincidence that the planning appeals with which the claimant is concerned were in progress at a time when the defendant’s decision was made it is clear, in my judgment, that the claimant would have shown no interest in challenging the lawfulness of the defendant’s decision. The claimant readily accepts that its sole purpose in challenging the defendant’s decision is to prevent it becoming material to the decisions to be made in the planning appeals in which the claimant is an objector.
30 During the course of the hearing there was some debate as to the status and/or relevance of the defendant’s decision in the planning appeals. I accept the submission of Mr Maurici that the defendant’s decision can be no more than a material consideration. It cannot be said, as was suggested by Mr Kimblin, that part of the reasoning of the defendant in support of his decision constitutes an expression of the defendant’s policy which would be binding upon an Inspector appointed by the Welsh Ministers to conduct the planning appeals in *82 which the claimant appears as an objector. Even if the defendant’s decision is treated as a material consideration by the Inspector considering the appeals I infer that it will be but one of a host of factors which will be considered. Mr Kimblin did not suggest before me that the acceptance of the defendant’s decision as a material consideration would be, in effect, determinative of the planning appeals.
31 In any event it must be borne in mind when assessing whether the claimant has a sufficient interest for the purposes of the Directive that if the defendant’s decision is treated as a material consideration and if the appeals are allowed the claimant has the ability to challenge those decisions under s 288 Town and Country Planning Act 1990.
32 Mr Maurici prays in aid the claimant’s ability to challenge any successful appeals under s 288 as a free standing reason why the defendant’s decision in these proceedings should not be the subject of judicial review. He may be right. In my judgment, however, the existence of this “alternative remedy” is also relevant, at least in the context of a case such as the present, in assessing whether the claimant is a member of the public concerned having a sufficient interest for the purposes of the Directive. I do not accept that this alternative remedy is illusory. It is illusory only if the claimant so conducts its affairs that it has no funds to mount a challenge under s 288 . That is a matter of choice for the claimant. In my judgment the existence of the right to challenge any decisions in the appellate process which are adverse to the claimant’s objectives is a factor which militates against the conclusion that the claimant is a member of the public concerned having a sufficient interest when challenging the defendant’s decision.
33 I have reached the clear conclusion that the claimant is not a member of the public concerned for the purposes of the Directive. That being so the Directive is not material to my decision upon whether or not to grant a protective costs order.
34 I should make two further points in this context for completeness. Mr Kimblin acknowledges that the claimant can bring itself within the Directive only if it establishes that it has a sufficient interest. It cannot, for example, assert that it is maintaining the impairment of a right; further, Mr Kimblin does not suggest that the claimant brings itself within the Directive because it is a nongovernmental organisation falling within the provisions of Article 1(2).”
Fifth, on 8 March 2011, the CJEU gave its decision in C-240/09 Lesoochranárske Zoskupenie VLK, in which it concluded, in relation to Article 9(3) of the Aarhus Convention and questions of standing, that while Article 9(3) did not have direct effect, it was for the national court “to interpret its national law in a way which, to the fullest extent possible, is consistent with the objectives laid down in Article 9(3) of the Aarhus Convention”.
A Slovakian association which had the objective of protection of the environment, applied to the Slovakian Ministry of the Environment to be a party to administrative proceedings relating to the grant of derogations to the system of protection for species such as the brown bear, access to protected countryside areas, or the use of chemical substances in such areas. This was rejected and this was challenged in the Courts. In those proceedings the Court made a reference to the CJEU as to the effect of art.9(3) of the Aarhus Convention.
The CJEU held that it had jurisdiction to interpret Art. 9(3) of the Convention. In this regard it noted that the PP Directive does not cover fully the implementation of the obligations resulting from Art. 9(3) of the Aarhus Convention and that, consequently, its Member States are responsible for the performance of these obligations. However, it found, it cannot be inferred that the dispute in the main proceedings does not fall within the scope of EU law because a specific issue which has not yet been subject to EU legislation may fall within the scope of EU law if it relates to a field covered in large measure by it. The CJEU held:
“45. It must be held that the provisions of Article 9(3) of the Aarhus Convention do not contain any clear and precise obligation capable of directly regulating the legal position of individuals. Since only members of the public who meet the criteria, if any, laid down by national law are entitled to exercise the rights provided for in Article 9(3), that provision is subject, in its implementation or effects, to the adoption of a subsequent measure.
46. However, it must be observed that those provisions, although drafted in broad terms, are intended to ensure effective environmental protection.
47. In the absence of EU rules governing the matter, it is for the domestic legal system of each Member State to lay down the detailed procedural rules governing actions for safeguarding rights which individuals derive from EU law, in this case the Habitats Directive, since the Member States are responsible for ensuring that those rights are effectively protected in each case (see, in particular, Case C-268/06 Impact  ECR I2483, paragraphs 44 and 45).
48. On that basis, as is apparent from well-established case-law, the detailed procedural rules governing actions for safeguarding an individual’s rights under EU law must be no less favourable than those governing similar domestic actions (principle of equivalence) and must not make it in practice impossible or excessively difficult to exercise rights conferred by EU law (principle of effectiveness) (Impact, paragraph 46 and the case-law cited).
49. Therefore, if the effective protection of EU environmental law is not to be undermined, it is inconceivable that Article 9(3) of the Aarhus Convention be interpreted in such a way as to make it in practice impossible or excessively difficult to exercise rights conferred by EU law.
50. It follows that, in so far as concerns a species protected by EU law, and in particular the Habitats Directive, it is for the national court, in order to ensure effective judicial protection in the fields covered by EU environmental law, to interpret its national law in a way which, to the fullest extent possible, is consistent with the objectives laid down in Article 9(3) of the Aarhus Convention.
51. Therefore, it is for the referring court to interpret, to the fullest extent possible, the procedural rules relating to the conditions to be met in order to bring administrative or judicial proceedings in accordance with the objectives of Article 9(3) of the Aarhus Convention and the objective of effective judicial protection of the rights conferred by EU law, so as to enable an environmental protection organisation, such as the zoskupenie, to challenge before a court a decision taken following administrative proceedings liable to be contrary to EU environmental law (see, to that effect, Case C-432/05 Unibet  ECR I2271, paragraph 44, and Impact, paragraph 54).
52. In those circumstances, the answer to the first and second questions referred is that Article 9(3) of the Aarhus Convention does not have direct effect in EU law. It is, however, for the referring court to interpret, to the fullest extent possible, the procedural rules relating to the conditions to be met in order to bring administrative or judicial proceedings in accordance with the objectives of Article 9(3) of that convention and the objective of effective judicial protection of the rights conferred by EU law, in order to enable an environmental protection organisation, such as the zoskupenie, to challenge before a court a decision taken following administrative proceedings liable to be contrary to EU environmental law.”
Sixth, there is the decision of the CJEU in Case C-115/09 Bund für Umwelt und Naturschutz Deutschland, Landesverband Nordrhein Westfalen eV v Bezirksregierung Arnsberg (judgment 12 May 2011). In that case Trianel – the intervener in the main proceedings – intended to construct and operate a coal-fired power station in Lünen. The power station was within eight kilometers of five areas designated as special areas of conservation within the meaning of the Habitats Directive. Friends of the Earth initiated proceedings for the annulment of consents granted for the power station relying on alleged infringements of the provisions transposing into German law the Habitats Directive and, in particular, Article 6 thereof. A reference was made to the CJEU. The issues raised was described thus by the CJEU:
“35 By its first two questions … the referring court asks essentially whether Article 10a of Directive 85/337 precludes legislation which does not permit non-governmental organisations promoting environmental protection, as referred to in Article 1(2) of [the EIA Directive] to rely before the courts, in an action contesting a decision authorising projects likely to have ‘significant effects on the environment’ for the purposes of Article 1(1) of Directive [the EIA Directive], on the infringement of a rule which protects only the interests of the general public and not the interests of individuals. The referring court also asks the Court whether Article 10a of [the EIA Directive] precludes such legislation in general or only in so far as it does not permit an organisation of that nature to rely before the courts on particular provisions of environment law, whether of Community or purely national origin.
36 It emerges from the order for reference that the question is justified by the fact that the applicable national legislation makes the admissibility of an action such as that brought by the applicant in the main proceedings conditional upon the applicant showing that the administrative decision contested impairs an individual right which, under national law, can be categorised as an individual public-law right.”
The CJEU held that:
“45 … although the national legislature is entitled to confine to individual public-law rights the rights whose infringement may be relied on by an individual in legal proceedings contesting one of the decisions, acts or omissions referred to in Article 10a of [the EIA Directive], such a limitation cannot be applied as such to environmental protection organisations without disregarding the objectives of the last sentence of the third paragraph of Article 10a of [the EIA Directive].
46 If, as is clear from that provision, those organisations must be able to rely on the same rights as individuals, it would be contrary to the objective of giving the public concerned wide access to justice and at odds with the principle of effectiveness if such organisations were not also allowed to rely on the impairment of rules of EU environment law solely on the ground that those rules protect the public interest. As the dispute in the main proceedings shows, that very largely deprives those organisations of the possibility of verifying compliance with the rules of that branch of law, which, for the most part, address the public interest and not merely the protection of the interests of individuals as such.
47 It follows first that the concept of ‘impairment of a right’ cannot depend on conditions which only other physical or legal persons can fulfil, such as the condition of being a more or less close neighbour of an installation or of suffering in one way or another the effects of the installation’s operation.
48 It follows more generally that the last sentence of the third paragraph of Article 10a of [the EIA Directive] must be read as meaning that the ‘rights capable of being impaired’ which the environmental protection organisations are supposed to enjoy must necessarily include the rules of national law implementing EU environment law and the rules of EU environment law having direct effect …
59. … non-governmental organisations promoting environmental protection, as referred to in Article 1(2) of that directive, can derive from the last sentence of the third paragraph of Article 10a of [the EIA Directive] a right to rely before the courts, in an action contesting a decision authorising projects ‘likely to have significant effects on the environment’ for the purposes of Article 1(1) of [the EIA Directive], on the infringement of the rules of national law flowing from Article 6 of the Habitats Directive, even where, on the ground that the rules relied on protect only the interests of the general public and not the interests of individuals, national procedural law does not permit this.”