Facts
The dispute concerns an international action to contest paternity. A.A., a Swiss national, and B.A., a Moroccan national, married in Switzerland in 1997. Their eldest son D.A. was born in 1999. The family moved to U. (France) in June 2009, and the spouses separated in April 2011.
On 26 March 2012, in X. (Switzerland), B.A. gave birth to the child C.A. A.A. was registered with the civil registry as the father, although it is not disputed that the biological father is E., who has since died and was domiciled in X. On 12 June 2012, A.A. informed the civil registry that he was not the father and that he disclaimed any responsibility.
On 21 May 2014, A.A. filed a petition for divorce before the Tribunal de Grande Instance of Y. (France). A proceeding to contest paternity was contemplated there but, according to A.A., it was never opened, B.A. having in the meantime moved to X. By order of non-conciliation of 5 November 2014, the French judge, among other things, fixed the child C.A.'s residence with his mother in [U.] and ordered A.A. to pay a maintenance contribution of 300 euros per month.
By penal order of 15 May 2017, B.A. was found guilty of forgery of documents for falsely announcing her arrival in Switzerland and forging A.A.'s signature. She acknowledged having lived in [U.] from 2009 to 2014.
On 18 November 2015, A.A. brought an action to contest paternity before the Court of First Instance of Geneva. B.A. requested dismissal, as did the child's guardian ad litem appointed on 9 February 2016. By judgment of 19 December 2016, the Court, applying French law and finding that the five-year time limit from the birth had been complied with, upheld the action and declared that A.A. is not the father of C.A.
By judgment of 23 January 2018, the Civil Chamber of the Geneva Court of Justice upheld B.A.'s appeal, set aside the first-instance judgment and dismissed all other claims of the parties. A.A. lodged a civil law appeal with the Federal Supreme Court, seeking annulment of the judgment and a declaration that he is not the father of the child.
Considerations
Under Art. 68 para. 1 PILA, filiation is governed by the law of the State of the child's habitual residence. Art. 69 para. 1 PILA fixes the date of birth as the decisive moment for determining that connecting factor. This rule does not necessarily apply, however, where a judgment on filiation is handed down several years after the birth and the child's habitual residence is no longer in the State of birth.
Under Art. 69 para. 2 PILA, where the child's legal status and social environment no longer coincide, the date on which the action was brought may be relied upon, provided that an overriding interest of the child so requires. This connecting factor is subsidiary to that of birth. The notion of overriding interest is not defined by the law or by the Federal Council's Message; it refers exclusively to the concrete interest of the child and must not be interpreted restrictively. This second connecting moment must be available to the child, even where the child is the defendant, when the date of birth is unfavourable to the child, in order to increase the child's chances of establishing or clarifying his or her filiation.
The Federal Supreme Court emphasises that Art. 69 para. 2 PILA is not a provision of public policy intended to displace foreign law in favour of Swiss law. Its application should therefore arise only in the event of a judicial dispute, where the judge finds that this connecting factor leads to the application of the law more favourable to the child in the case at hand, which requires reference to the foreseeable outcome of the proceedings. In ATF 129 III 288, the…