During his confirmation hearings, Judge John Roberts, the Chief Justice of the United States of America, famously admitted that he was aware of the fact that millions of people had elected the US Congress and not even one person had voted for the Supreme Court. More recently, in the now famous Obamacare judgment pronounced on June 28, Roberts declared that it was not the job of the Supreme Court to “protect people from their political choices”. Such is the deference for the legislative branch of the government in the country that literally invented the doctrine of judicial review.
Justice Iftikhar Chaudhry, the Chief Justice of Pakistan, recently told his audience at the Karachi registry of the Supreme Court that in Pakistan it is not the parliament but the constitution that is sovereign. Any student of political science or constitutional law will be able to see clearly the fallacy in such a statement. Parliamentary sovereignty and the constitution are distinct concepts and cannot be substituted. Therefore if the parliament is not sovereign as the Chief Justice says, it calls into question the status of the constitution as a higher law. The theory of constitution as higher law rests entirely on the sanction it receives from a pouvoir constituent. Admittedly, in contrast to the English constitution, where there are written constitutions with rigid procedure for amendment, the parliament acts in two capacities – legislative and constituent. The written constitution provides a framework and legislation has to be undertaken in that framework. However, the fact that a parliament can at will amend the constitution makes it sovereign and supreme.
A valid argument against parliamentary sovereignty would be that the constitution is not a higher law and not the fundamental law of the land. The Chief Justice has taken a self contradictory position ie arbitrarily vesting sovereignty and supremacy in a document but putting the parliament that has the power to amend the constitution beneath it.
Technically in a pure parliamentary democracy, the only limit on a parliament’s power is when it tries to clip its own wings as shown in Jackson and Others v Attorney General  1 AC 262 [Jackson].