Abstract In HKSAR v Lui Sai Yu [2023] HKCFA 26, the Hong Kong Court of Final Appeal (CFA) delivered its first judgment on the mandatory sentencing regime under the newly introduced National Security Law (NSL). Adopting a common law approach to interpreting the NSL, the CFA held that mitigating factors not listed in the NSL cannot bring about a sentence below the minimum prescribed by the relevant provision. In this article, we propose an alternative approach to interpreting the NSL. We argue that, contrary to the CFA’s rejection of any reference to Mainland Chinese laws in constructing the NSL, both a common law purposive approach and the principle of ‘convergence, compatibility and complementarity’—one of the working principles in the enactment of NSL—would support such reference. The implications of our proposed approach would be to (i) recognize that the sui generis nature of the NSL, being a Chinese national law applied in its Special Administrative Region of Hong Kong, necessitates the consideration of relevant Chinese legal norms; and (ii) allow for a broader range of mitigating factors—those recognized by both Hong Kong common law and Mainland Chinese law—to be applied to the minimum sentencing regime in the interest of fairer and more principled outcomes for defendants.