Federal Supreme Court, 20.04.2026, 1C_323/2025
Facts
B.________ SA has obtained a building permit from the Geneva Department of Territory for a 22-unit housing project on plot no. 88 in Pregny-Chambésy. Access to this plot is via Chemin D., which has a maximum width of 4.20 meters. A neighboring company, A. SA, appealed this authorization, first to the Court of First Instance (TAPI), and then to the Administrative Chamber of the Court of Justice. During the proceedings, the Department issued a new permit, identical to the first but including a parcel mutation project aimed at dividing the land to comply with quotas for minor construction projects (CDPI). The cantonal authorities rejected the successive appeals by A.________ SA, considering in particular that access for fire services was sufficient and that taking the parcel mutation project into account was admissible. A.________ SA then appealed to the Federal Supreme Court, primarily challenging these two points. (Facts A, B, C, D)
Legal Analysis
The Federal Supreme Court reiterates that its power of review is limited when it comes to the application of cantonal law, which it reviews only for arbitrariness. A decision is arbitrary if it is manifestly unsustainable, contradicts the sense of justice and equity in a shocking manner, or violates a clear rule. It is not enough for the reasoning to be unsustainable; the result of the decision must also be so. Similarly, facts established by the lower authority can only be corrected if they are manifestly inaccurate (arbitrary) or established in violation of the law (c. 2.1.1, 2.1.2).
Regarding fire service access, in construction matters,Art. 19 para. 1 of the Federal Act on Spatial Planning (SPA) requires that land be served by access routes adapted to its use in order to be considered developed. This includes guaranteeing sufficient access for emergency services. Cantonal and municipal authorities have broad discretion in this area. However, the Federal Supreme Court specifies that the specific issue of fire service access, when governed by detailed cantonal standards such as Geneva Directive no. 7, falls under cantonal law and not the federal concept of development. The review is therefore limited to arbitrariness (c. 2.1.3).
The appellant argued that Chemin D.________ was too narrow, in violation of cantonal directive no. 7. The Federal Supreme Court notes that the cantonal court relied on several elements: a "Fire Safety Concept" report, a favorable opinion from the fire police, and, above all, a "Fire Truck Test" expert report demonstrating that the passage of a ladder truck was concretely ensured. The Federal Supreme Court judges that, even if the exact width of the path was not measured at every point, the cantonal court's approach is not arbitrary. Since the purpose of the cantonal standard—to guarantee effective firefighter access—is achieved, the decision is not arbitrary in its result. The fact that the truck might encroach on the part of the path belonging to the appellant is deemed non-determinant for exceptional use (c. 2.2, 2.3).
Regarding minor construction projects (CDPI), the applicable Geneva cantonal law (former Art. 3 para. 3 RCI) set a maximum surface area of 100 m². The question arises as to whether a parcel division project, not yet entered in the land register, can be taken into account to verify compliance with this quota (c. 3.1). The appellant argued that it was arbitrary to base calculations on a parcel mutation project that was not yet effective. The Federal Supreme Court upholds the cantonal court's approach. The latter had ruled, referring to a departmental directive, that it was possible to take such a project into account and that it would be disproportionate to require its registration in the land register before the building permit became final. The Federal Supreme Court confirms that it is not unsustainable to consider that the division project, being a condition of the permit (point 15 of the decision), is an integral part of it. The permit itself guarantees that the mutation must be carried out. As this reasoning is not arbitrary, the grievance is rejected (c. 3.2).
Outcome
The Federal Supreme Court rejects the appeal to the extent that it is admissible. Legal costs are charged to the appellant, A.________ SA, which must also pay legal fees to the respondent, B.________ SA.
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