The rule of recognition, as coined and defined by HLA Hart, is increasingly used as an organising principle in UK constitutional discourse. Student textbooks and leading judgments have in the past 20 years begun to explain and analyse parliamentary sovereignty as the UK’s rule of recognition. Yet this usage is mistaken. The issues Hart was interested in are rarely – if ever – at stake in public law discourse or adjudication. The rule of recognition analysis neither coheres with nor explains developments in the UK constitution in recent decades. The explicitly political nature of key aspects of the UK constitution makes a strict positivist approach to constitutional doctrine all the more peculiar. At a time of significant constitutional uncertainty, a broader legal realist account of doctrinal change and adaptation by judges and politicians is required.