Over the past 30years, changes in judicial power have been accompanied by a com-petition between the several modes by which that power is legitimated: sometimes polite and sometimes fractious. Each mode of legitimation brings to bear its own view of the judicial role, its source of authority and supporting normative frame-work which together constitute a particular interpretation of judicial culture and its contribution to the British constitution. As both judicial powers and modes have changed, so the constitutional tensions have increased with Parliament and the exec-utive becoming belatedly aware that their relationship with the judiciary is not all that they would wish. Under the impact of Brexit and the demands this placed on the judiciary, the character of the political contest between the competing modes of legitimation on which judicial power relies has become more intense, visible and disputatious as the modes have been stretched and tested by the institutional colli-sions Brexit has evoked. With the implementation of Brexit now in train and devolu-tion firmly on the political agenda, the politics of legitimation can only become yet more evident as the role and power of the judiciary are drawn inexorably further into the public domain.