Kernrechtsfrage
Whether the Nidwalden courts could hear the defendant's counterclaim in the seller's forum under Article 59 BV.
Extrahierter Entscheid
No. In inter-cantonal proceedings, a counterclaim in the forum of the main action is admissible only if it is materially connected with the main claim; that requirement was absent here.
Extrahierte Begründung
The claim and counterclaim arose from entirely separate legal transactions and the counterclaim was directed against a different person in substance. The cantonal courts therefore lacked constitutional competence to decide the counterclaim.