The purpose of legislation according to Madison was to deal with general principles. Legislation should be about general principles not about details of policies. The function of the legislature in Madison's view is not to espouse or promote "various and interfering interests". Thus, Madison (the most influential of the draftsmen of the US Constitution) thought that legislation is primarily concerned with the determination of what Hayek was to later call "the rules of just conduct". Madison refers to "the good of the whole", "the common good", "the public good" and "the interest of the people" in relation to the proper aim of government. However, Madison's idea of the public good is very different from that of the modern interventionist.
Delegation of the law making function is inevitable in the modern state. The objectionable aspects of delegation which have undermined the rule of law are: the sheer magnitude and volume of delegated legislation, the abdication by Parliament of its duty to lay down "general principles" and the inordinate extent of uncontrolled discretions that have been conferred on the executive.
The control by Parliament over "general principles" is important for the functioning of the democratic order. Parliament is elected by and responsible to the electorate. Parliament is elected on the basis of its manifesto which constitutes its mandate. If Parliament is restricted to legislation on "general principles", electoral control over Parliament and also over the executive is a possibility. The executive must act within the confines of laws passed by Parliament — otherwise it will be subject to the doctrine of "ultra vires" (acting beyond authority) and its actions will be invalid. The people may compare legislation with the Party manifesto and pass judgment. The control over Parliament and the executive by the electorate breaks down due to: (i) the sheer volume of delegated legislation, and (ii) delegation to the executive of legislative power on matters of "general principle".