What is Known: • Parents have wide discretion in deciding for their child in everyday life, while far-reaching treatment decisions should align with the child’s best interest. • Shared decision-making harbours potential conflict between parental authority and a child’s best interest. What is New: • The best interest standard should not be used narrowly as a way of saying “Yes” or “No” to a specific action, but rather in a coherent framework and process which we term the shared optimum approach. • By supporting this child-centred and family-oriented process, shared decision-making becomes crucial in implementing the best interest standard.