The Singapore courts often state that judicial review of executive decision-making ought only to involve an inquiry into the ‘legality’ of a decision or the ‘decision-making process’, and not the ‘decision itself’ or its ‘merits’ – let us call this the ‘Distinction’. This article argues that the Distinction should be expunged from Singapore law. The Distinction has its roots in English case law which aimed to prevent the courts from arbitrarily substituting their decision for the executive's by reason of mere disagreement. But Singapore case law has gone further and treated the Distinction as a general principle applicable to all of administrative law. However, the Distinction is too vague for this purpose (as seen from Singapore cases which have interpreted the distinction inconsistently). It is conceptually problematic, incompatible with the practicalities of judicial review (particularly substantive review as recognized in Singapore law), and has occasionally been paid lip service but not followed in substance. The Distinction cannot form a coherent principle to guide the courts and ought to be replaced by a more nuanced application of constitutional principles relevant to determining the appropriate scope of review. Whatever these principles may be, and however they are to be balanced, the Distinction can be but an over-inclusive rough approximation of them which hampers the development of the law.