The constitutional law of a country may be defined as that portion of its fundamental law which prescribes or determines the structural character of the various governmental organs included in its total political organisation, their relations inter se, and the particular powers and functions of each of them.
So wrote Andrew Inglis Clark, one of the chief architects of the Australian Constitution. As he pointed out, constitutional law is only one part of the entire law of a country, but it is arguably the most fundamental. Constitutional law defines and regulates the institutions by which a country is governed. These governing institutions typically have the authority to make law, to enforce the law and to resolve disputes about the content and application of the law. Constitutional law is thus concerned with ultimate questions about what the law is, how the law can be changed and who has the authority to make law, interpret its meaning and enforce it.
Another highly influential framer of the Australian Constitution, Robert Garran, defined a constitution as follows:
A Constitution is a general law for the government of a political community, unamendable and unrepealable, except in the manner and on compliance with the conditions prescribed by the authority which created it. It deals with the sovereign power of Government and the various forms, organs, and agencies through which that power is brought into action and the relations, interdependence, and co-operation of those forms, organs, and agencies, in the performance of the work of government.
On Garran’s view, a constitution is a special type of law which not only defines and regulates the government, but which exists by virtue of an authority that is distinct from the ordinary institutions of government and which can only be altered in accordance with conditions prescribed by that authority. When Garran said this, although he was speaking generally, he undoubtedly had the Australian Constitution specifically in mind. This leads to several questions. What, on his view, was the authority by which the Australian Constitution had come into being? By what authority or special procedures could it be amended? How does it define the sovereign power of government?