Question

When can a law passed by parliament be declared null and void?

Answer 1

If the subject legislated on is from the State list of the Constitution, or if the provisions of the law have the effct of denying the citizen the Fundamenta Rights of that citizen,the Law can be struck down as Unconstitutional

Under the British Parliamentary System, it is my understanding that nothing is superior to an act of Parliament.

Perhaps the Sovereign could withhold assent, but that would certainly create a crisis.