NM, a South African citizen, and MBM, an Australian citizen, married and lived together in Brisbane, Australia, where their child, NEM, was born and habitually resident. In September 2022, NM travelled with NEM to South Africa with MBM’s consent for a holiday, with agreed return tickets. Before the return date, NM informed MBM that she would not return to Australia and retained NEM in South Africa. MBM, with the assistance of the Central Authority of South Africa, instituted Hague Convention proceedings for NEM’s return. NM opposed the application, raising a defence under Article 13(b) (grave risk of harm) and, shortly before the hearing, launched a counterapplication challenging the constitutionality of s 275 of the Children’s Act 38 of 2005. The High Court ordered NEM’s return to Australia, separated the constitutional challenge from the main application, and rejected the Article 13(b) defence. NM appealed to the Supreme Court of Appeal.