Question juridique clé
Whether the appellate court violated constitutional rights by treating the slope's pre-existing stability and vegetation as insufficiently contested.
Solution extraite
No constitutional violation was shown; the court could require a substantiated denial of those facts under the adversarial system.
Motifs extraits
Only contested facts must be proven. The appellants did not specifically challenge the slope's prior stability or natural vegetation in the cantonal proceedings, so the court did not misapply burden-of-proof rules or act arbitrarily.