Pioneered by the US, recent mega-regional trade agreements such as the CPTPP have incorporated ‘regulatory coherence’ provisions—mirroring the US Administrative Procedural Act's core designs—to balance between domestic regulatory autonomy and international cooperation. Building upon existing literature that traces the trajectories of the diffusion of regulatory coherence across jurisdictions, this article analyses how Australia's constitutional tradition could effectively condition the development of regulatory coherence in a Westminster-based model of governance. It is argued that the global entrenchment of regulatory coherence is contingent upon the inherent boundary defined by the political dynamics and constitutional structures within a jurisdiction.