It is important to put things into perspective here.
The question is actually about the limits on the powers of Parliament to amend the constitution. It is being said in this thread by my colleagues that it is not possible and cannot happen since it will be tantamount to playing with the soul of the constitution and that the judiciary will strike it down.

In the case of Pakistan, I believe, things are complex because the case law has not been fully developed in this regard.

I want to make two points :

a) Judiciary can strike down an ordinary legislation in Pakistan like it does in most other countries. However, can judiciary strike down an amendment to the constitution is still a moot point. This question was taken up by the courts when the 18th amendment was challenged. However, the superior court only dealt with the aspect of the appointment of judges and left the rest of the points made against 18th amendment to be decided later. (The case is still pending) . In India, as we all know, the courts have come up with the doctrine of basic structure according to which the parliament does not have unlimited powers to amend the constitution and that even with the 2/3 rd majority the parliament cannot amend the basic structure of the constitution(Kesavananda Bharti case-1973). The Indian SC itself identified the features of the basic structure. However, it is only Indian courts ,and in one case a Bangladesh High court, that accept and use this doctrine.
Our courts in Pakistan are yet to decide upon it. In some cases such as mahmood achakzai case and lawyer's forum case, SC did talk about the essential features of the constitution, it is yet to identify them.
So, can Pak SC strike down an amendment is still a moot point and not yet decided.
Nonetheless,as constitutionalists say, the question of the parliament waking up one day to decide anything 'fantastical' doesn't arise because of the same simple old fact: It is eventually not the force of law but that of public opinion which is the real sanction behind any action

b) As far as the Objective resolution (O.R) is concerned, its actual place lies in the preamble and not in the constitution proper where it was inserted by Zia via 2(a). Preamble may be a soul or a guiding light, it is not a substantive part of the constitution and hence not judicable. Which is why Zia felt the need to make it substantive with his notorious 8th amendment. He did so for dubious purposes which will be discussed some other time. Nonetheless, it should be mentioned that the SC in "Hakim khan case and Kaniz fatima case(1992-93) " has already held that O.R should not be used and cannot be used to strike down a legislation and that it is not grundnorm. The same position was perhaps repeated by the SC in its NRO nullification order.

Hope it will help to shed some light...

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Why not !?