Key legal question
Whether the child had just cause under Art. 30 CC to change his surname to the father's name
Extracted holding
No. The child did not show concrete social disadvantages from bearing the mother's surname, and the asserted family-integration and bilingual-nationality arguments were insufficient.
Extracted reasoning
Just cause exists only when the applicant's interest in a new name outweighs the public and administrative interest in stability and identification. Here, the mother bore the same surname as the child, so the child was not isolated within the household; dual nationality and foreign registration alone did not justify a change; and family-integration concerns were not better served by the father's surname.