is the idea that Parliament
is at the top of the political system.
In the UK there is also a convention that when passing a law, Parliament cannot pass a law which binds the next Parliament. This removes the possibility of having an entrenched and codified constitution unless one first removes parliamentary sovereignty since a constitution will bind any future governments. It is also this lack of a constitution that led to this position of having parliamentary sovereignty in the first place.
It used to be the case that the Monarch was sovereign but this was changed with the passing of the Bill of Rights 1689 which changed the old monarchy into a constitutional monarch. This act also altered the relationship of Parliament (among other things). It was now made sovereign instead of the monarch.
This means that in the UK, the judiciary cannot stop a bill that Parliament wishes to pass. Unlike in the States where the Supreme Court can strike down an act passed through the executive and the legislature if it is unconstitutional, the UK judicial system has no such power. This has been slightly altered with the introduction of the Human Rights Act which allows the judiciary to rule that a bill contravenes our human rights (it still cannot strike that bill down but its better than nothing).
Since joining the European Union, it has been suggested that Parliamentary sovereignty has been damaged. Since membership of the EU means that the member has to accept European policy it means that the next Parliament cannot just repeal an act made under the last Parliament (which was made to keep in line with the EU). It is suggested that this damages Parliamentary sovereignty but Parliament can still repeal the act that joined us to the EU in the first place and therefore sovereignty is retained.
The same is true with the Human Rights Act 1998. This makes it possible for the judiciary to question bills that can be seen as unconstitutional. This strikes at the heart of Parliamentary sovereignty since Parliament should not be questioned (it is sovereign). However, it is important to note that the Labour government did make sure that the act only allows the judges to question the constitutionality of the bill, not strike it down. Therefore parliamentary sovereignty is preserved to some extent. It also is important to note that Parliament can remove this Act whenever it wishes (though it would have to leave the EU as well).
if anyone can offer insights into this in other political systems in other countries (or the UK if I have missed something) then /msg me or email me (see my home node).