Practical Limitations

From even the brief analysis of Dicey's doctrine examined above, it can be seen that the concept of parliamentary supremacy has never been practically implemented to its logical conclusion, and it is all but inconceivable that it ever would be. In addition to the sheer logical absurdity of a parliament answerable to absolutely no one, however, the modern era has provided many other concrete, explicit, and practical impediments to true parliamentary sovereignty. Some of these impediments have been domestic in nature, and thus could be considered untested if practically apparent; others, however, are international in nature and can be seen as constituting a conscious, willing, and explicit reduction of parliamentary supremacy.

Domestically speaking, there have been a series of judicial decisions that would seem to limit parliamentary supremacy, insisting that judicial review is necessary in the case o fcertain legal formations and applications (Allan, 2011). Others have noted that the fundamentals of federalism, which are responsible for dispensing authority within the United Kingdom and for keeping the nation together as a political unit, are simply incompatible with the existence of any unitary or supreme authority, parliamentary or otherwise, thus making Dicey's doctrine of parliamentary sovereignty a false premise for any federalist nation (Walker, 2000). Legal practice has continued to demonstrate that the application of British law does not recognize a true sovereignty as existing in the parliament; though this is the highest legal entity in the United Kingdom,...

The Human Rights Act passed by the European Union, for example, is a major piece of legislation that explicitly sets up courts and certain other bodies external to the United Kingdom that are explicitly granted sovereignty over certain issues (Anthony, 2002). There are other agreements with the European Union and other member nations, as well as decisions made within other European Union member nations that have been made applicable to other member nations and the European Union as a whole, that further limit the true sovereignty or supremacy of the United Kingdom's parliament both when it comes to the nation's external actions and in some of its domestic affairs (Weatherhill, 2007; Harker et al., 2011). All such agreements explicitly and directly negate the notion of parliamentary supremacy.
Conclusion

It is clear from even a basic analysis that the concept of parliamentary supremacy is not applicable in the modern era, and was ultimately incorrect when the doctrine was first advanced. While parliament holds supremacy in that it is the highest body within the government in the United Kingdom, in practice the parliament is limited by certain codified and un-codified laws and principles. Understanding this is essential t properly understanding UK constitutionality.