This paper theoretically discusses two different legal paradigms and connects them with contemporary legal practices in Pakistan to analyze the contours of constitutional judiciary and its writ prerogative. It argues that judicial review of legislation and administrative actions is core of constitutionalism in the American liberal jurisprudential context. As this model is based on the Kantian perspective of ‘categorical imperative’ which indicates that rightful conditions for egalitarians cannot be compromised in any cost. And for sustainability of such rightful conditions, the contractarian philosopher like Kant focuses on the institution of judiciary to protect and promote liberties and rightful conditions in a society. Whereas in the British model of conventionalism, supremacy of parliament is a core premise to maintain rule of law in society as for this context law represents a collective aspiration of a community which emerges through parliamentary excellence. And judiciary as delegate of sovereign is only supposed to ascertains vires of law but not the constitutional validity of law which rests in parliamentary domains. Both of these models focus on the aspirations and collective wisdom of society and intend to protect them through respective institutions. Although Pakistan’s legal system is based upon British model due to the continuity of colonial laws after its inception. Yet also contains American conception of egalitarians through objective resolution of 1949, which contemporarily forms an operative part of constitution 1973 under the Article 2A. However in Pakistan neither judiciary nor parliament has evolved as such to cater socio economic justice and rightful conditions due to continuous interventions of military coups, autocratic administrative patters. Interestingly the latter two are usually justified through Dicey’s perspective of ‘executive prerogative’ and ‘doctrine of state necessity’ which he had evolved in British model as a last resort to protect realm against any unusual perils. For Dicey it was a ‘rule by law’ instead of ‘rule of law’ yet again under parliamentary domains and for a limited period to counter emergencies for which judiciary has no remedy. But then in Pakistan such rule by law context is instrumentally relied upon either through presidential executive orders or through provisionally constitutional orders especially when constitution itself has been held in abeyance during proclamation of martial laws. Due to this indigenous novelty neither ‘rule of law’ as espoused by neither British model nor ‘due process of law’ as espoused by American model function in its entirety in Pakistan. Study identifies this aspect as the vulnerabilities of constitutionalism and judicial review in Pakistan.