The European Court of Justice (ECJ) has broken new ground, ruling for the first time on criminal law, until now the exclusive domain of national courts within the EU.
The ECJ said Italian courts had followed an EU "framework decision on the standing victims in criminal proceedings" when allowing young children to give evidence-in-chief at a preliminary hearing for sexual offences.
It added that the Italian judges should "conform to the wording" of the EU decision "as far as possible".
ECJ judges noted that, in cases affecting police and judicial cooperation within criminal matters, EU member states could accept European jurisdiction, and Italy has made such a declaration.
The European Commission hailed the ruling as "historic", saying it would "considerably strengthen the legal instruments availableÃ¢Â€Â¦ in criminal matters".