<![CDATA[Background: Article 37(1) of the 1961 Vienna Convention on Diplomatic Relations (VCDR) extends immunity to diplomatic family members on a derivative basis, while Article 32 does not oblige the sending State to waive that immunity, even where credible allegations of modern slavery arise. The UK Supreme Court's decision in Basfar v. Wong expanded accountability through the commercial activity exception but left unresolved the legal position of diplomatic family members and the consequences of waiver refusal. Methodology: The research employs normative legal research using statutory and case approaches supported by doctrinal analysis. Objectives: This article examines the derivative nature of diplomatic family immunity and whether a sending State's refusal to waive immunity may engage State responsibility under the Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA) 2001. Findings: Diplomatic family immunity under Article 37(1) is derivative and requires a separate express waiver under Article 32. Although Article 32 does not impose a legal duty to waive immunity, refusal in the face of credible allegations of modern slavery may engage the sending State's due diligence obligations under ARSIWA 2001, potentially giving rise to cessation and reparation. Originality/Novelty: The article identifies and analyses the unresolved normative gap concerning diplomatic family immunity and waiver refusal following Basfar v. Wong while distinguishing between lex lata and lex ferenda]]>
