Article 1, Section 7, Clauses 2 and 3
William Blackstone, Commentaries 1:149--51, 1551765
It is highly necessary for preserving the ballance of the constitution, that the executive power should be a branch, though not the whole, of the legislature. The total union of them, we have seen, would be productive of tyranny; the total disjunction of them for the present, would in the end produce the same effects, by causing that union, against which it seems to provide. The legislature would soon become tyrannical, by making continual encroachments, and gradually assuming to itself the rights of the executive power. Thus the long parliament of Charles the first, while it acted in a constitutional manner, with the royal concurrence, redressed many heavy grievances and established many salutary laws. But when the two houses assumed the power of legislation, in exclusion of the royal authority, they soon after assumed likewise the reins of administration; and, in consequence of these united powers, overturned both church and state, and established a worse oppression than any they pretended to remedy. To hinder therefore any such encroachments, the king is himself a part of the parliament: and, as this is the reason of his being so, very properly therefore the share of legislation, which the constitution has placed in the crown, consists in the power of rejecting, rather than resolving; this being sufficient to answer the end proposed. For we may apply to the royal negative, in this instance, what Cicero observes of the negative of the Roman tribunes, that the crown has not any power of doing wrong, but merely of preventing wrong from being done. The crown cannot begin of itself any alterations in the present established law; but it may approve or disapprove of the alterations suggested and consented to by the two houses. The legislative therefore cannot abridge the executive power of any rights which it now has by law, without it's own consent; since the law must perpetually stand as it now does, unless all the powers will agree to alter it. And herein indeed consists the true excellence of the English government, that all the parts of it form a mutual check upon each other. In the legislature, the people are a check upon the nobility, and the nobility a check upon the people; by the mutual privilege of rejecting what the other has resolved: while the king is a check upon both, which preserves the executive power from encroachments. And this very executive power is again checked, and kept within due bounds by the two houses, through the privilege they have of enquiring into, impeaching, and punishing the conduct (not indeed of the king, which would destroy his constitutional independence; but, which is more beneficial to the public) of his evil and pernicious counsellors. Thus every branch of our civil polity supports and is supported, regulates and is regulated, by the rest; for the two houses naturally drawing in two directions of opposite interest, and the prerogative in another still different from them both, they mutually keep each other from exceeding their proper limits; while the whole is prevented from separation, and artifically connected together by the mixed nature of the crown, which is a part of the legislative, and the sole executive magistrate. Like three distinct powers in mechanics, they jointly impel the machine of government in a direction different from what either, acting by themselves, would have done; but at the same time in a direction partaking of each, and formed out of all; a direction which constitutes the true line of the liberty and happiness of the community.
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These are the constituent parts of a parliament, the king, the lords spiritual and temporal, and the commons. Parts, of which each is so necessary, that the consent of all three is required to make any new law that shall bind the subject. Whatever is enacted for law by one, or by two only, of the three is no statute; and to it no regard is due, unless in matters relating to their own privileges. For though, in the times of madness and anarchy, the commons once passed a vote, "that whatever is enacted or declared for law by the commons in parliament assembled hath the force of law; and all the people of this nation are concluded thereby, although the consent and concurrence of the king or house of peers be not had thereto;" yet, when the constitution was restored in all it's forms, it was particularly enacted by statute 13 Car. II. c. 1. that if any person shall maliciously or advisedly affirm, that both or either of the houses of parliament have any legislative authority without the king, such person shall incur all the penalties of a praemunire.
The Founders' Constitution
Volume 2, Article 1, Section 7, Clauses 2 and 3, Document 1
The University of Chicago Press
Blackstone, William. Commentaries on the Laws of England: A Facsimile of the First Edition of 1765--1769. Chicago: University of Chicago Press, 1979.
Easy to print version.