[(2018) 5:2 JICL 461–483] AUTONOMY, DEFERENCE AND CONTROL: JUDICIAL DOCTRINE AND FACETS OF SEPARATION OF POWERS IN SINGAPORE Jaclyn L Neo* Abstract: This article examines judicial engagement with the idea of separation of powers in Singapore. It identifies and analyses three judicial doctrines that are explicitly justified by the courts as being underpinned by the separation of powers. These are the doctrine of the exclusivity of judicial power, the doctrine of the presumption of constitutionality and the doctrine of judicial review. In analysing these doctrines and how the courts have employed the separation of powers to justify them, this article points to differing conceptions of separation, namely separation as autonomy of the different branches of government, separation as deference to the political branches and separation as judicial control of the other branches of government. Keywords: judicial power; judicial review; deference; autonomy; separation of powers; constitutionalism; parliamentary supremacy; constitutional supremacy I. Introduction While the separation of powers has been judicially declared in Singapore to be “fundamental and essential” to its political system 1 and part of its basic structure, 2 there has yet to be a close examination of what judges mean when they refer to the separation of powers. In particular, what a commitment to separation of powers requires in terms of constitutional doctrine is not always clear. This article seeks to address this gap by examining how the separation of powers has been explicitly discussed and propounded upon in constitutional law cases in Singapore. To be sure, there are many views of what a theory of separation of powers requires and many dimensions to the requirements of separation. An article seeking to examine and critique the mechanics of separation of powers may furthermore take on different institutional perspectives and subject matters. Being aware of the multiplicity of * Associate Professor, Faculty of Law, National University of Singapore. I would like to thank Arif Jamal, HP Lee, Kevin YL Tan and Mark Tushnet for reading previous drafts and Louis Lai for his research assistance. 1 Yong Vui Kong v Public Prosecutor [2015] 2 SLR 1129, [71] (CA). 2 Mohammad Faizal bin Sabtu v Public Prosecutor [2012] 4 SLR 947, [11] (HC); Yong Vui Kong v Public Prosecutor, Ibid.; Ravi s/o Madasamy v Attorney-General [2017] 5 SLR 489, [66] (HC). JICL 5(2).indb 461 JICL 5(2).indb 461 05/11/18 4:15 PM 05/11/18 4:15 PM