Article 4
1. By way of derogation from the second paragraph of Article 2, Member States may, on their national territory, permit children aged three years and over occupying the seats of vehicles referred to in Article 1 to be restrained by a safety belt or other restraint system approved for adult use. 2. Member States shall also, on their territory and under conditions specified in their national law, allow that children under three years of age occupying rear seats need not be restrained by a restraint system suitable for their height and weight if such children are transported in a vehicle where such a system is unavailable.