Facts
On May 26, 1989, various persons concluded a simple partnership for a real estate development project called "X." in Versoix (Geneva). Two partners, H. and [C.], did not have the necessary funds to make their contribution, so [A.] agreed to lend them the money.
According to an agreement dated October 1, 1991, [A.] lent [C.] the sum of CHF 124,500, with interest at the rate of the second-rank mortgage "currently 8.5%". On August 3, 1994, the same parties signed a loan agreement for the sum of CHF 16,000, with interest at the rate of the second-rank mortgage "currently 6%". On October 11, 1996, [A.] terminated both loans for the end of the year. As [C.] had not paid either the principal or the interest, [A.] initiated debt collection proceedings.
Considerations
The cantonal court found that the interest rate on the second-rank mortgage had not been proven for the loan period. According to Art. 8 CC, the creditor claiming payment of interest had to prove the facts to establish the amount of his claim. The lack of evidence therefore led to a decision in his…