The claimant, a recognised environmental protection association, asserts a claim against the defendant district, to prevent the use of a bicycle track.

The Elster bicycle track, in part still under construction, runs from the Elster source in Czechia to the Leipzig lowland bay. The subsection (section 4) of the road section between Asch and Oelsnitz at issue here, starts south of Adorf at the federal highway B 92, crosses the "Weiße Elster" by way of a bridge, continues its way parallel to the water to the north and ends on a site in the town of Adorf. To a considerable part, it is situated in the special area of conservation under the Habitats Directive (Habitats Directive Area) "Elstertal oberhalb Plauen". Its protective objectives are amongst others to conserve predominantly semi-natural running water sections with minor alder-riverside forest and waterside shrub land as well as to preserve or to re-establish a favourable conservation status for certain animal and plant species.

The defendant carried out the construction project in the aforementioned subsection without environmental impact assessment, and due to the alleged minor importance of the project, refrained from initiating a planning approval procedure (Planfeststellungsverfahren). In the course of construction works, existing roads were enlarged to a width of predominantly 2.50 m and were paved; the old bridge was replaced.

Upon action filed, the Administrative Court had ordered the defendant in accordance with the application to prevent the use of the road within the Habitats Directive Area for all types of traffic by way of suitable means until completion of the planning approval procedure including an environmental impact assessment, whether with or without public participation . The Higher Administrative Court dismissed the defendant's appeal on points of fact and law.

10 The admissible appeal on points of law is partly founded. The judgment of the court of appeal is not in every regard in line with federal law (section 137 (1) Code of Administrative Court Procedure (VwGO, Verwaltungsgerichtsordnung)) and insofar does not prove to be correct in its result either (section 144 (4) VwGO). Since additional factual findings are needed, the judgment is to be quashed and remitted to the Higher Administrative Court for proceedings and ruling pursuant to section 144 (3) sentence 1 VwGO).

11 1. While, contrary to the defendant's view, the action is admissible in its scope still pending.

12 a) The claimant's right to bring legal proceedings results from section 2 (1) in conjunction with section 1 (1) of the Environmental Appeals Act (UmwRG, Umwelt-Rechtsbehelfsgesetz) as still applicable here in its version of 8 April 2013 Federal Law Gazette (BGBl., Bundesgesetzblatt) I p. 753) last amended by act of 20 November 2015 (BGBl. I S. 2069). (…)

14 The right to bring legal proceedings in the interest of the general public conferred to an association includes the right to institute an action for administrative intervention against a project built and operated without a decision on the required permission (…).

17 The objective of the rules under sections 1 and 2 UmwRG in particular argues for this result. It namely consists in transposing applicable standards of European and International law into national law. Pursuant to article 11 (1) and (3) of the Directive 2011/92/EU of the European Parliament and of the Council of 13 December 2011 on the assessment of the effects of certain public and private projects on the environment (OJ L 26, p. 1) - (EIA Directive) -, which itself is based on article 9 (2) and (3) of the Aarhus-Convention, the Member States are under an obligation to grant access to environmental associations to a review procedure (before a court of law) "to challenge the substantive or procedural legality of decisions, acts or omissions". The environmental associations have the possibility to have the legal provisions originating from Union law reviewed comprehensively without restriction to subjective rights (Court of Justice of the European Union (ECJ), judgments of 12 Mai 2011 - C-115/09 [ECLI:EU:C:2011:289], Trianel - para. 45 et seq. and of 15 October 2015 - C 137/14 [ECLI:EU:C:2015:683] Commission v Germany - para. 33). This applies without regard to whether the obligation to conduct an environmental impact assessment arises already conclusively from article 4 (1) in conjunction with annex I of the EIA Directive or whether it arises from article 4 (2) in conjunction with annex II of the EIA Directive and the legal provision of the Member States as is the case in other road projects not mentioned in annex I.

18 The obligation to cure the unlawful consequences of a breach of the law also results from Union law. Where there is a failure to conduct an environmental impact assessment, the competent authorities as well as the courts are required to take all and any measures to effectively cure such shortcoming. They must take the suitable and proportional "measures to suspend" provided by national law in order to prevent the plan or the project to be put into effect without the prescribed environmental impact assessment (ECJ, judgment of 28 February 2012 - C 41/11 [ECLI:EU:C:2012:103], Inter Environnement Wallonie - para. 43 et seqq. with further references). Just as suspending construction, closing down a project illegally built on procedural grounds is in principle a suitable measure in terms of the principle of effectiveness, resulting in an environmental association being able to force its adoption by bringing legal action in court. (…)

20 2. However, on the merit, the Higher Administrative Court, based on the findings so far, should not have upheld the first instance judgment allowing the claim.

21 a) In complying with federal Law, the Higher Administrative Court held that section 3 (2) of the Federal Nature Conservation Act (BNatSchG, Bundesnaturschutzgesetz), whose scope of application is not limited but enlarged by section 2 sentence 1 of the Nature Conservation Act of the State of Saxony (SächsNatSchG, Sächsisches Naturschutzgesetz) (see article 72 (4) first sentence no. 2 of the Basic Law (GG, Grundgesetz)), provides a proper legal basis for the requested measure. Accordingly, the authorities competent for environmental conservation and landscape preservation supervise compliance with the provision of this law as well as compliance with the provisions adopted on the basis of this law and, unless otherwise provided, in accordance with proper exercise of discretion, adopt the measures required in each individual case in order to ensure compliance with such provisions. Section 3 (2) half sentence 2 BNatSchG lays down the power to intervene, inspired by the general clause under police law, which, as a general rule, applies next to other authorities' competing powers to intervene and which is put into execution by the competent nature conservation authority in its capacity of a special regulatory authority (…). As decided by the Higher Administrative Court in applying federal state law, the defendant, as legal entity of the lower environmental conservation authority (untere Naturschutzbehörde), is competent to this effect. The Higher Administrative Court could not identify any superseding special provisions and such provisions are not evident to the Senate either.

22 The preconditions laid down in the elements of section 3 (2) half sentence 2 BNatSchG are fulfilled in the case here at issue. As correctly elaborated by the Higher Administrative Court and as is now undisputed between the parties, the project carried out without a planning approval procedure and thus without environmental impact assessment, is in violation of procedural and substantive nature conservation law. For, according to the result of the assessment on the impact on the Habitats Directive Area commissioned by the defendant, the finished construction considerably adversely effects the conservation objectives of the Habitats Directive Area concerned, causing the only way to legalise it to be a deviating decision - in view of the adverse effects on a priority natural habitat with the involvement of the EU-Commission - (article 6 (3) and (4) of Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora <OJ. L 206 p. 7> - Habitats Directive, section 34 (3) and (4) BNatSchG). Under such circumstances, putting the project into effect without involving the claimant is also in violation of section 63 (2) no. 5 BNatSchG; for, within the meaning of this provision, the general inadmissibility of this project with considerable adverse effects is deemed a "prohibition" and the deviating decision an "exemption" thereof (BVerwG, judgment of 1 April 2015 - 4 C 6.14 - Rulings of the Federal Administrative Court (BVerwGE, Entscheidungen des Bundesverwaltungsgerichts) 152, 10 para. 12 with further references).

23 b) The Higher Administrative Court further held that, under the present circumstances, the defendant's discretion to prevent such use was reduced to one remaining lawful decision. This is not in compliance with federal law.

24 aa) Pursuant to section 3 (2) half sentence 2 BNatSchG, the decision to intervene is, as a general rule, left to the proper exercise of discretion of the competent environmental conservation authority (including the discretion on the decision whether to act and on the choice of means to be employed). The violation of nature conservation law alone does not in itself result in the failure to intervene to constitute an error of discretion. However, a particularly serious violation of nature conservation law may result in a reduction of discretion; this applies increasingly so, the more precious, sensitive and scarce the natural asset concerned. Under such circumstances, the provisions of Union law in particular, lead to a reduction in the scope of discretion provided for by national law. In order to prevent considerable adverse effects for a Habitats Directive Area, the authority is, as a general rule, under an obligation to intervene (…).

25 Against this background, the Higher Administrative Court assumed that the discretion to issue a prohibition to use was reduced, where a street was built or expanded in a Habitats Directive Area without first carrying out the required planning approval procedure. The construction-related interference in the Habitats Directive Area had been "further intensified" without other aspects, in particular security aspects, demanding a different assessment in the present case. Under the given circumstances, the defendant rightfully opposes this view. (…)

26 From a Union law perspective, the question, whether there is an imperative obligation to prevent the use of a road built without first assessing the implications for the Habitats Directive Area, is to be judged by applying article 6 of the Habitats Directive. Contrary to the claimant's view, article 6 (3) of the Habitats Directive shall not be applied directly in this regard. The question, whether this provision, if so required, in conjunction with the duty of loyalty arising from article 4 (3) of the Treaty on the Functioning of the European Union (TFEU), is to be interpreted to the effect that a Member State has to close down a project realised without the required assessment until such assessment has been carried out, can, without submission to the European Court of Justice (article 267 TFEU), clearly be judged on the basis of the past jurisprudence of the Court of Justice. Article 6 (3) of the Habitats Directive provides for an assessment procedure which, by way of previous control, is supposed to warrant that projects are not granted approval except to the extent that they do not adversely affect the area as such. Therefore, this provision does apply only, if a national authority approves a project without such assessment. It does however not apply to activities requiring permission but carried out unlawfully without such permission (ECJ, judgment of 10 November 2016 - C-504/14 [ECLI:EU:C:2016:847], Commission v Greece - para. 120 et seqq.).

27 Rather, the standard of review whether there is an obligation to close down an unlawfully completed construction is the general duty to protect under article 6 (2) of the Habitats Directive, which is related to section 6 (3) and is supposed to warrant the same level of protection for natural habitats and habitats of species (ECJ, judgment of 14 January 2016 - C-339/14 [ECLI:EU:C:2016:10], Grüne Liga Sachsen e.V. - para. 36 et seq., 52 with further references). Insofar it is sufficient but also necessary that there is a probability or danger that the operation of the structures originating from an unauthorised project, causes a considerable disturbance of the conservation objectives of the area; there is no need to establish the existence of a causal link (ECJ, judgments of 14 January 2016 - C-399/14 - para. 42 and of 10 November 2016 - C-504/14 - para. 29). Whereas, in the last-mentioned judgment, the Court of Justice held the concrete risks for natural habitats and habitats of species established by an expert opinion, correlating with the use of unauthorised roads, to be sufficient to constitute an infringement of article 6 (2) of the Habitats Directive. However, to the extent that such concrete risks did not exist, it denied such infringement (judgment of 10 November 2016 - C-504/14 - para. 53 et seqq.).

28 bb) On this basis, in the present case, findings by made by the judges of fact are needed as to whether and to what extent any further temporary use of the bicycle track until completion of the subsequently initiated planning approval procedure, may reasonably give rise to concrete fears over considerable adverse effects on the conservation objectives of the Habitats Directive Area in excess of the construction-related disturbances. On the one hand, a connecting factor is the point in time immediately following the listing of the Habitats Directive Area. To the extent that the initial roads, later built over in the course of this controversial project, did already exist and were already in use, this shall be factored in as prior encumbrance. On the other hand, one must take into consideration that the construction-related interference has ended. Whether and to what extent it has to be undone will depend on the outcome of the planning approval procedure. Under these circumstances, one must examine, whether there is a likelihood or danger of additional use-related deteriorations. The assessment on the impact on the Habitats Directive Area commissioned by the defendant, which has already been prepared and which, if need be, is to be explained by the authors, may serve as a basis for such examination.

29 Where there is a concrete risk of additional use-related deteriorations, the discretion of the defendant on whether to intervene in order to prevent such deterioration is, as a general rule, reduced to one remaining lawful decision (Ermessensreduzierung auf Null). Exceptionally, something different may only apply, where public interests of considerable weight, in particular such of road safety, are opposed to closing down the structure. Where the defendant must intervene against such use, the defendant must, within the discretion conferred to him on the means to employ, decide whether such use is to be prevented completely, or whether restriction of use in time, space or otherwise are sufficient in order to avoid additional relevant environmental conservation related disturbances.

30 Where there is no reasonable need to fear additional use-related deteriorations, the defendant's discretion on whether to intervene against the temporary use of such unlawfully built structure, is, as a general rule, not reduced to one remaining lawful decision. This applies - as is the case here - whenever the project does not consist of a new construction but of the expansion of a traffic road already existing in the sphere of the Habitats Directive Area. In such case, as a general rule, weighing is needed in each individual case, factoring in not only nature conservation interest but also the interests of the users of the traffic road (here in addition to cyclist also pedestrians and farmers). Exceptional circumstances may however reduce administrative discretion in such constellation, where applicable, they may even turn into an obligation to prevent such use. As already elaborated in another context, the obligation of authorities as well as of courts to cure the consequences resulting from a breach of environmental law as characterised by European law follows from Union law (ECJ, judgment of 28 February 2012 - C41/11 - para. 43 et seqq. with further references). Where there is a wrongful failure to carry out the prescribed planning approval procedure including an environmental impact assessment prior to the commencement of the construction - as is the case here - it must not only be initiated subsequently but must also be completed without delay. Where, as a result, it turns out that a permission for the structure built cannot be granted, such structure must, in case of need, be modified or removed (see also BVerwG, judgment of 15 July 2016 - 9 C 3.16 - (…)). Where the procedural steps needed in this regard are being delayed, prohibiting the use can suggest itself in order to add authority to the command to rectify errors. (…)