Questão jurídica principal
Whether the debtor could set off a claim against the child’s mother against advanced child-support claims transferred to the municipality.
Decisão extraída
No. Set-off requires mutuality; child-support claims belong to the child, so a claim against the mother is not reciprocally matchable with the support debt, and the legal cession to the municipality did not cure that defect.
Fundamentação extraída
Under Art. 120 OR, mutuality is required. Under Art. 289 ZGB, the child remains creditor; the parent merely receives performance as legal representative. A claim against the mother cannot therefore be set off against the support debt, neither before nor after legal subrogation to the municipality.