Facts
On 3 May 1999 the Birmenstorf Municipal Council granted the then owner [D.] a building permit for the conversion and extension of a grazing shed and for the partial change of use to horse keeping on parcel No. 745 in the agricultural zone. The permit was linked to a removal undertaking (Beseitigungsrevers), applicable in the event that the abandonment or substantial reduction of the sheep or horse stock, or the minimum roughage base of 5.26 ha, no longer existed.
In 2009, unauthorised alterations to the stable were identified. The Department of Construction, Transport and Environment (BVU), Building Permits Division, rejected the subsequent building application on 29 July 2010 and ordered the demolition. The Government Council (29 June 2011) and the Administrative Court (27 February 2012) dismissed the appeals; the demolition order has been legally binding since 2012. The BVU did not enter into a request for reconsideration dated 4 March 2013; the Government Council dismissed the administrative appeal on 26 February 2014, insofar as it entered into the matter, and the Administrative Court and the FSCA (judgment 1C_462/2015 of 22 February 2016) confirmed this.
The appellants, who until then had been tenants of the parcel, submitted on 2 and 23 December 2016 a building application for the conversion and extension of the stable, which was qualified as a request for reconsideration. In spring 2018 they acquired parcel No. 745. The Administrative Court upheld an appeal against the decision not to enter into the matter, because the change of ownership had altered the circumstances, and remitted the matter to the Municipal Council. The latter rejected the request for reconsideration on 21 January 2019. The Administrative Court dismissed the direct appeal (Sprungbeschwerde) on 22 August 2019.
By public-law appeal, the appellants requested that the lower court's judgment be set aside, that the matter be remitted for approval of the request for reconsideration, that the stable not be demolished and that the demolition order not be enforced. The Administrative Court and the BVU requested non-entry into the matter or, alternatively, dismissal. The Municipal Council wished to retain the stable, so far as legally possible, for a use conforming to the zone. The Federal Office for Spatial Development expressed its views without a specific application, but demanded that the appellants no longer be granted further delays. By presidential order of 23 October 2019, suspensive effect was granted to the appeal.
The question in dispute is whether the lower court infringed federal law by rejecting the request for reconsideration and the building application for the stable despite the earlier permit, by assessing the stable as not objectively necessary at this location, and by requiring its demolition.
Considerations
Admissibility: The challenged decision is a final cantonal decision in a public-law matter (Art. 86 para. 1 lit. d FSCA; Art. 82 lit. a FSCA). The appellants, as building applicants and owners of the stable to be demolished, have standing to appeal (Art. 89 para. 1 FSCA). Whether there is obstructive litigation conduct or appellate criticism may be left open, since the appeal is in any event unfounded. The request for an on-site inspection is rejected, as the facts are sufficiently apparent from the file.
Consideration of the unlawfulness: The stable was originally erected solely on the basis of an exceptional permit with a removal undertaking. Since 2009, unauthorised alterations have been repeatedly carried out, and since 2012 a legally binding demolition order has existed. The fact that the stable still stands despite this order must not work to the appellants' advantage. The situation must be assessed as if the unlawful stable had already been demolished, since otherwise persons building illegally would be placed in a better position than builders acting in compliance with the law (judgment 1C_233/2017 of 19 September 2018 E. 6.4). The reference to the agricultural use conforming to the zone is also unhelpful, because non-compliance with regulations must not be rewarded with a subsequent building permit (spatial planning interests under Art. 3 SPA). Furthermore, no entitlement to continuation of the unlawful state can be derived from years of use despite the demolition order. The Administrative Court's earlier wording, that this was not a true new construction, related only to the question of entry into the matter and does not establish a reversal of position.
Necessity of location: Under Art. 16a para. 1 SPA and Art. 34 para. 1 SPO, only buildings necessary for agricultural cultivation conform to the zone in the agricultural zone. Under Art. 34 para. 4 lit. a-c SPO, the builder must prove the objective necessity of the building at the chosen location, demonstrate a protected interest in that site, not allow overriding interests to oppose it, and document the long-term existence of the operation (BGE 125 II 278 E. 3a). The choice between sites is in principle a question of law subject to free review, although the Federal Supreme Court exercises restraint where local or technical questions are concerned and specialist bodies have decided.
The lower court was entitled to assess the location as not objectively necessary: in view of the public interest in avoiding urban sprawl, any operationally necessary additional requirement would have to be met at the operating centre located roughly 700 m away. This corresponds to the principle of concentration (BGE 141 II 50 E. 2.5; judgment 1C_58/2017 of 18 October 2018 E. 5.4.1). The appellants…