What is the 'grave risk of harm' defense under the Hague Convention and how hard is it to prove?

The grave risk defense allows a court to refuse to return a child under the Hague Convention where doing so would expose the child to a grave risk of physical or psychological harm, or otherwise place the child in an intolerable situation. It's one of the narrowest and most difficult defenses to establish, precisely because the Convention is built around discouraging unilateral removals and restoring the situation that existed before the wrongful removal, rather than allowing the receiving country to relitigate the whole parenting dispute under the banner of this defense.

Courts require clear and compelling evidence of a serious, specific risk to the child, not general concerns about parenting quality, a preference for one country's schools or standard of living, or the disruption of returning itself. Family violence directed at a parent or child can support this defense, but courts often also consider whether protective measures available in the child's home country — such as undertakings or protective orders — could adequately address the risk, which can result in a return being ordered subject to specific conditions rather than refused outright.