Facts
The Burri spouses rented the "Altstadt" hotel in Arbon from the Moeri brothers for a period of five years as of August 1, 1979. The initial rent was CHF 2,000 per month, then increased to CHF 2,500 per month as of January 1, 1980. The rental agreement provided that the rent could be adjusted based on the evolution of the mortgage interest rate. The Moeri brothers repeatedly requested a rent increase, which the Burri spouses refused.
The Moeri brothers brought a lawsuit to have it declared that the requested rent increases were not abusive. The court of first instance dismissed their request, and the Moeri brothers appealed to the cantonal court. The cantonal court also dismissed their request, considering that the clause of the rental agreement relating to the adjustment of the rent based on the mortgage interest rate was null and void.
The Moeri brothers filed an appeal with the Federal Tribunal, requesting the annulment of the cantonal court's decision and the declaration that the clause of the rental agreement was valid and that the requested rent increases were not abusive.
Considerations
The Federal Tribunal considered that the cantonal court had violated federal law by not treating the Moeri brothers' request to have the validity of the clause of the rental agreement relating to the adjustment of the rent based on the mortgage interest rate declared. The Federal Tribunal estimated that this clause was valid, as it did not allow the Moeri brothers to unilaterally and without justification increase the rent.
The Federal Tribunal also considered that the cantonal court had erred in considering…