Facts
Y. and X. lived in a de facto union from mid-1980 to spring 1982. On July 6, 1981, X. gave birth to son W., and Y. acknowledged him as his child on July 10, 1981. After the couple's separation, the contact between Y. and W. more or less broke off, with Y. continuing to pay the indexed maintenance payments according to the maintenance agreement.
After reaching the age of majority, W. filed a claim with the District Court of Wil for the revocation of Y.'s paternity and the establishment of Z.'s paternity. The DNA expert opinions established Z.'s paternity, whereupon he took over the maintenance contributions retroactively from March 2000.
On November 29, 2000, Y. filed a claim against Z. for unjust enrichment for the maintenance contributions not yet absolutely time-barred, amounting to CHF 78,787.50.
Considerations
The Federal Supreme Court holds that the application of the provisions of the Code of Obligations to family law relationships is generally permissible, insofar as the Civil Code or the rest of private law does not conclusively regulate a matter. Since the Civil Code does not contain any rules on the recourse of child maintenance, the application of the provisions on unjust enrichment is justified.
The plaintiff (registered father) can reclaim the maintenance contributions, as he was under an error when acknowledging the child, and until the expiry of the challenge period, no events have occurred that would have obliged him under the…